"Hello, I had a bad experience with Whiteflash. The diamond looked good on paper and was recommended by sales lady, who inspected it personally."
"But to me looked like a piece of glass. Not sure what went wrong. I'm looking for a 2 ct., diamond ring + diamond band , GIA Excellent, tiffany quality stone with excellent "sparkle".
"Looking to spend around around ±$20k. These are some that seemed ok to me but I may be focusing too much on clarity so I pulled up a vs1 last. I think fluorescence medium might be a good thing."
The GIA Excellent Cut Diamonds from Blue Nile:
Shattering the Glass Ceiling of GIA Excellent Cut Diamonds:
As you can imagine, I am curious to see how the diamond you purchased from Whiteflash looks like glass. The optical properties of diamond vary dramatically from stone to stone. Subtle differences in proportions and optical precision can have dramatic effects on light performance.
Send me a link to the diamond details page for the Whiteflash diamond so that I may look at the specifications. Knowing the proportions and being able to judge the degree of optical precision will enable me to help you make a better choice.
In the mean time, let's take an in-depth look at the GIA Excellent cut diamonds you found on Blue Nile. Now you know that not all ideal cut diamonds are created equal. In that case, you'll want to fine-tune the parameters and focus on diamonds that offer the best light performance and sparkle factor.
Blue Nile Reviews: LD07539559
The 1.91 carat, G-color, VVS-2 clarity, GIA Excellent cut round diamond from Blue Nile has a total depth of 62.7% which is very steep by my standards.
The critical tipping point where light begins not to strike fully off the pavilion facets (lower half of the diamond) is 43.5%.
The pavilion depth of this diamond is 44% which is most likely creating the obstruction (light leakage) visible under the table facet in the form of the black asymmetrical shapes indicated by the red arrows in this clarity photograph provided by the supplier.
Notice that the arrows pattern of this diamond is translucent and lacking contrast. This means that this diamond has poor contrast brilliance. From this vantage point, the pavilion main facets (which create the arrows pattern) should be dark because they are reflecting back the dark color of the camera lens.
Since the arrows pattern is translucent, I can only assume that the pavilion main facets are not at the correct angle to reflect back the dark color of the camera lens. The lack of contrast brilliance might be due to the proportions or the axis of the facets might be off kilter.
This is What Exceptional Contrast Brilliance Looks Like:
Here's a photograph of the engagement ring that Brian Gavin made for my son. This Black by Brian Gavin heart and arrows diamond exhibits exceptional contrast brilliance.
Now be aware that in real life, the arrows pattern will not be this dark. The arrows pattern appears dark in this photograph because the pavilion main facets are reflecting the dark camera lens that is directly over the diamond.
However, the higher degree of contrast brilliance which creates this effect will make the diamond seem like it is sparkling more. Consequently, this happens even when the diamond is being viewed in lighting situations where diamonds don't really sparkle. For example, under fluorescent lighting that lacks ultra-violet.
The Total Depth of 62.7% Makes This Blue Nile Diamond Look Smaller!
In addition to affecting the light performance of this diamond in a negative manner, the steep total depth also makes the diamond look smaller. This 1.91 carat round brilliant cut diamond from Blue Nile measures 7.93 x 7.89 x 4.96 mm.
In that case, he diamond has an average outside diameter of X millimeters (7.93 + 7.89 = 15.82 / 2 = 7.91 mm).
This 1.906 carat, G-color, VS-2 clarity, Black by Brian Gavin hearts and arrows round diamond has an average outside diameter of 7.98 mm. This diamond has a total depth of 61.3% and measures 7.97 X 7.99 X 4.89 mm.
The pavilion depth of 40.7 degrees will produce a high volume of light return. The crown angle of 34.6 degrees will produce a virtual balance of brilliance (white sparkle) and dispersion (colored sparkle).
Creating Broad-spectrum Sparkle:
The combination of the higher degree of optical precision that creates the hearts pattern and the 78% lower girdle length will produce broad-spectrum sparkle.
It will also produce a higher number of virtual facets which are the internal prismatic kaleidoscope-like reflections of light created by the overlapping facet pattern. The higher number of virtual facets produces more sparkle and the sparkle will be more vivid and intense than what standard ideal cut diamonds tend to exhibit.
In my experience, a lower girdle facet length between 75 - 78% produces a really nice looking arrows pattern. While lower girdle facets in the range of 80% or higher tend to produce thinner looking arrows. Lower girdle facets that measure around 82% tend to look weak and spindle-like.
The challenge is that the GIA rounds off the lower girdle facet length to the nearest 5% so you have to be able to visually estimate the lower girdle facet length. That is one of the reasons I prefer the AGS Light Performance ASET based grading platform, because the AGS doesn't round off the measurements after averaging them (let that sink in for a minute).
The Downside of Super Ideal Cut Diamonds:
The only downside to the super ideal cut diamonds from Brian Gavin, is that they cost more. At least, compared with standard ideal cut diamonds because they take longer to produce. In fact, it takes four times longer to polish the diamonds to exhibit the higher degree of optical precision.
Time is money as they say and diamond cut quality can affect the price of a diamond by up to sixty percent. At the same time, why are you buying a diamond if not to enjoy the incredible sparkle?
With this in mind, I tend to focus on diamond cut quality above all else and then nudge things like clarity and color around to adjust the price.
The reality is that you will be able to see the difference in sparkle across the room, but you won't be able to see the difference in clarity or color from across the dinner table.
In fact, most people have difficulty distinguishing subtle differences in clarity or color from more than a foot or two. Above is the side profile of the engagement ring that Brian Gavin made for my son Corey. The setting is the Diana Platinum by Brian Gavin that has been set with 4 mm green Tsavorite accents.
As you can see, it creates a very unique look that is quite striking. Actually, Corey's fiancé loves emeralds. However, they are too soft to be set in a ring that will be worn every day. So, we chose Tsavorites because they are more durable.
Blue Nile Reviews: LD09942264
This 2.01 carat, G-color, VVS-2 clarity, round brilliant cut diamond from Blue Nile has a total depth of 62.5%. The diamond measures 7.97 x 8.06 x 5.01 mm. That means that the outside diameter is almost one millimeter out of round.
The average outside diameter is 8.015 millimeters which is smaller than this 1.99 carat, E-color, VS-1 clarity, Brian Gavin Signature hearts and arrows round diamond.
There is More to Carat Weight than Meets the Eye:
The 1.99 carat, Brian Gavin Signature round diamond (above) measures 8.05 X 8.10 X 4.99 mm. Thus, it has an average outside diameter of 8.075 mm.
Why is this important? Because the 1.99 carat diamond faces-up larger than the 2.01 carat diamond and there is a MAJOR PRICE INCREASE that occurs between 1.99 - 2.00 carats.
This means that if you buy the preceding diamond from Blue Nile, that you're paying a premium for a 2.01 carat diamond but getting a diamond that faces-up smaller than two carats!
As of today, the difference in the base Price Per Carat (PPC) between 1.90 - 1.99 carats, G-color, VVS-2 clarity and 2.00 carats is $5,800.00 per carat.
While super ideal cut diamonds like those produced by Brian Gavin command a premium, you're getting a lot more sparkle for your money.
While money spent on carat weight that is hidden in total depth is totally wasted and usually results in a lesser degree of light performance. Obviously, the 1.99 carat, Brian Gavin Signature round diamond is beyond the budget you have in mind.
Consequently, I'm not suggesting that you buy it. However, it serves as a good example of the difference in visible outside diameter that results from cutting to tighter proportions.
Brian Gavin Advance Ideal Diamond Review:
This 2.101 carat, I-color, VS-2 clarity, Brian Gavin Signature hearts and arrows diamond is similar to the one I chose for my own ring.
The diamond I chose for my wedding ring was also produced by Brian Gavin. The reality is that all diamonds tend to look amazing under jewelry store halogen lighting.
What impresses me about these diamonds is how they sizzle in sunlight and look incredible in low light environments.
First, the 40.7 degree pavilion angle will produce a high volume of light return. Second, the 34.8 degree crown angle will produce a virtual balance of brilliance and dispersion.
At the same time, the higher degree of optical precision and the 75.6% lower girdle facets will produce the broad-spectrum sparkle that we're looking for in a diamond.
Will an I-color diamond look yellow set in platinum or white gold:
It goes without saying that I-color is going to face-up a little warmer than G-color, but not that much. Especially if you set the diamond in white gold or platinum because it will reflect back the color of the white metal.
An I-color diamond set in white gold or platinum is likely to face-up more like H-color. While setting the same I-color diamond in yellow gold will make it face-up closer to J-color. The color of the ring itself is of little consequence, it is the color of the prongs that touch the edge of the diamond that affects our perception of color.
Circling back to the 2.01 carat, G-color, VVS-2 clarity, round brilliant cut diamond from Blue Nile. There is a little bit of obstruction at the base of the arrows, but it is less apparent than in the other diamond.
The extra depth appears to be making the diamond look a bit dark under the table facet and my guess is that it's leaking a bit of light. We would need an ASET/Ideal Scope image to tell for sure, but Blue Nile does not provide those images.
Blue Nile Reviews: LD09970009
This 2.01 carat, G-color, VVS-2 clarity, GIA Excellent cut round diamond from Blue Nile exhibits a lot of obstruction between the arrows.
I've added red arrows to the clarity photograph to make it easier for you to identify. If you click on the line drawing of a diamond in the face-up position under the video frame for diamonds on Blue Nile (highlighted in green) you will be able to see the clarity photograph.
This diamond has a total depth of 60.1% which is great. However, the table diameter is 62% and that's not good. It seems like whenever the table diameter of a round diamond is larger than the total depth then the diamond leaks lots of light.
That certainly seems to be the case in this situation. In fact, this diamond appears to be leaking light along the edge of the table facet. How do I know? Look at the light brown/tan areas along the edge of the table facet. The light leakage is most apparent in the zone between 11 o'clock to three o'clock.
If you look closely at the arrows pattern and table facet region of this diamond you will see how the larger table facet creates a bit of a black hole effect. It looks like the arrows pattern is pulling you inward. Also notice how the arrow shafts seem shorter in length and the wagon wheel look that it creates.
Blue Nile Reviews: LD00007594
This 2.01 carat, G-color, VS-1 clarity, GIA Excellent cut round diamond from Blue Nile is a tricky case because the proportions seem pretty good. The 40.8 degree pavilion angle should produce a high volume of light return.
The 35.5 degree crown angle is just a little steeper than my preferred range which is between 34.3 - 35.0 degrees. The most likely effect of the steeper crown angle is that it might create a hint more dispersion.
Click on the icon of a line drawing of a diamond under the video frame (highlighted here in green) to see the diamond in the face-up position. Now that the diamond isn't spinning around in a circle, you can see how light is reflecting through the diamond.
Once again, this "GIA Excellent Cut" round diamond has a lot of obstruction under the table facet. I didn't point it out this time because I'm certain you're able to see it now for yourself.
At the same time, I want to teach you how to spot light leakage without an ASET/Ideal Scope. Take note of the discoloration indicated by the red arrows that appears along the edge of the table facet. Now take a look at the ASET Scope image provided by the supplier.
ASET Scope Images for Blue Nile Diamonds:
That entire translucent zone along the edge of the table facet is light leakage. Notice how it is more apparent in the four to seven o'clock region? Now imagine the diamond rotated 90 degrees and look at the clarity photograph again.
I ran a search on Blue Nile for GIA Excellent cut diamonds with proportions within my preferred range. I set the upper limits for price at $23K in hopes of finding something interesting.
The best option I found is this 2.02 carat, G-color, VS-2 clarity, GIA Excellent cut round diamond from Blue Nile. Unfortunately, it doesn't exhibit very good contrast brilliance and there is some obstruction between the arrows.
In that case, I expanded the search to include other dealers. Consequently, I found two other options that are worthy of consideration. Consequently, you might be wondering where I found an ASET Scope image for a Blue Nile diamond.
I didn't get it from Blue Nile. As a registered member of the trade, I have access to the multiple listing services that the industry uses to market diamonds globally. Many of the suppliers provide clarity photographs and reflector scope images for the diamonds in their inventory.
James Allen True Hearts Review: AGS 104095765013
This 2.05 carat, I-color, VS-2 clarity, James Allen True Hearts diamond has a pavilion angle of 40.9 degrees which should produce a high volume of light return.
The 35.0 degree crown angle should produce a virtual balance of brilliance and dispersion. The 76% lower girdle facet length and higher degree of optical precision should produce broad-spectrum sparkle.
Note that the Ideal Scope image indicates the beginning of light leakage under the table facet (light pink areas) but it is better than the options from Blue Nile. That means that this diamond should deliver a higher volume of light return and sparkle which is more vivid and intense.
Generally speaking, I find that the degree of optical precision exhibited by James Allen True Hearts diamonds is better than most GIA Excellent cut diamonds. However, it is not up to the standards of Brian Gavin Signature diamonds. From my perspective, James Allen True Hearts diamonds offer a good middle ground between the spectrum of standard and super ideal.
James Allen True Hearts Diamond Review: AGS 104095588001
Things are a little better with this 2.12 carat, I-color, VS-2 clarity, James Allen True Hearts diamond. The 40.9 degrees which should produce a high volume of light return.
The 34.3 degree crown angle should produce a virtual balance of brilliance and dispersion. The 77% lower girdle facet length and higher degree of optical precision should produce broad-spectrum sparkle.
The Ideal Scope image still shows a hint of light leakage (the light pink areas along the edge of the dark arrows under the table facet). However, the light performance of these diamonds is substantially better than the options you found on Blue Nile.
Which is not to say that you can't find some great looking diamonds on Blue Nile. The hunt for the perfect diamond often involves a bit of luck and can be a bit like looking for a needle in a haystack. While the diamonds we found on Blue Nile today don't meet my selection criteria, the reality is that we might find some great looking diamonds another day.
Keep in mind that diamond cut quality can affect the price of a diamond by as much as sixty percent. With this in mind, you might need to increase your budget if you want to maintain the higher clarity and color. Let me know if you would like to adjust things and please send me the link to the diamond you originally purchased from Whiteflash.
Whiteflash Expert Selection Diamond Review: GIA 6187522461
I was really curious about the characteristics of the diamond this client purchased from Whiteflash. As you recall, this client thought that the Whiteflash diamond looked liked a piece of glass.
So, I asked the client to send me the diamond grading report number and any images that he might have of the diamond.
The client forwarded me a copy of the email sent to him by Whiteflash, which contained a video of the diamond and images.
I was not able to locate the diamond on Whiteflash by lab report number. However, I was able to find the 2.11 carat, I-color, VVS-2 clarity, GIA Excellent cut round on Enchanted Diamonds.
The two translucent sections under the table facet in the relative five to seven o'clock region indicate light leakage. There are also some lighter pink areas along the edge of the table facet. That indicates light leakage to a much lesser extent that is similar to the James Allen True Hearts diamonds from above.
Sub-par Light Performance from Ideal Proportions? How is that possible?
What might be confusing to people is that the proportions of this diamond are spot-on. The 40.8 degree pavilion angle should produce a high volume of light return. While the 35.0 degree crown angle produces a virtual balance of brilliance and dispersion.
The 75% lower girdle facet length is producing arrows that are good size and this should produce sparkle that is bold and bright. The 50% star facet length is right on the money. So, what is going on?
You might wonder why this "ideal cut diamond" is leaking so much light under the table facet? It's not the proportions of the diamond that are causing the light leakage, it's the degree of optical precision or lack thereof.
Optical Precision is the Missing Piece of the Diamond Cut Quality Puzzle:
Optical precision is the consistency of facet shape, facet size, and the alignment of the facets as they are indexed on to the surface of the diamond.
The gemological laboratories do not take optical precision into account as part of the symmetry grade! Which is why reflector scope images, such as the ASET Scope, Ideal Scope, and Hearts & Arrows Scope images that I frequently refer to are of such importance!
Do you see the black asymmetrical shapes along the edge of the arrows pattern from the two o'clock to six o'clock position? Imagine rotating the diamond so it aligns with the ASET Scope image. Then, you will see how the leakage and dark areas are related.
GIA Excellent & AGS Ideal-0 Represent a Range of Cut Quality:
People tend to assume that AGS Ideal-0 and GIA Excellent cut diamonds are simply the best, but nothing could be farther from the truth. The reality is that each cut grade represents a range or spectrum of cut quality. As such, there is going to be a low-end, a mid-range, and a high-end.
This 2.11 carat, I-color, VVS-2 clarity, GIA Excellent cut from Enchanted Diamonds (the Whiteflash diamond) falls in the middle of the spectrum. The proportions of the diamond are within what we consider to be "the sweet spot" but the diamond is leaking a fair amount of light. Let's take a look at the images from the perspective of an experienced diamond buyer like myself:
Remember: Diamond Cut Quality Affects Price (by up to 60%)
All right, you already know that the red arrows in the clarity photograph represent light leakage. Those areas are also clearly evident in the multi-colored ASET Scope image (upper right) and the red Ideal Scope image (lower right).
The yellow arrows on the ASET Scope image indicate areas where the diamond is leaking light to a lesser extent. The yellow arrows on the hearts image do not indicate light leakage, but rather issues with the optical precision.
To that regard, the most critical factor are the tips of the hearts which are bending. This effect is created by differences in the length of the lower girdle facets. The spacing around the hearts is also uneven and this is contributing to the light leakage more than you might imagine.
The clefts of the hearts are also split and all of these factors explain why this diamond is not delivering the light performance you might expect from an ideal cut diamond.
Consequently, it is essential to realize that the client selected this diamond from the virtual inventory that WhiteFlash offers. It is not a WhiteFlash A CUT ABOVE™ diamond. In other words, it is not one of their hearts and arrows diamonds.
Who Cuts the Best Super Ideal Cut Diamonds?
The fact that my son Corey purchased his engagement ring from Brian Gavin speaks volumes, don't you think? The 35+ years I've worked in the industry as a diamond buyer and consultant enables us to buy from practically any diamond cutter in the world.
We chose Brian Gavin because his diamonds exhibit the most spectacular light performance we've ever seen on a consistent basis. And consistency is the key to knowing where to buy a super ideal cut diamond.
Because you don't want to wonder whether the diamond you're buying is going to deliver exceptional light performance. You want to know that your diamond is going to exhibit incredible sparkle factor without question, right?
That's why my son Corey bought his diamond engagement ring from Brian Gavin, that's why he selected a diamond from the Brian Gavin Black collection.
Look at the precision of the hearts pattern! The hearts are much more even in size and shape. The spacing around the hearts is significantly better. There are no splits in the clefts of the hearts.
Perfect is a Relative Concept:
It is important to realize that you're never going to find a perfect pattern of hearts and arrows. That's because these diamonds are turned on the wheel by hand. The goal is to find diamonds that exhibit a higher than average degree of optical precision. Diamonds like this one from the Brian Gavin Black collection.
The kind of diamond that a professional diamond buyer with 30+ years of experience would pick-out for his son. The kind of diamond that I would buy for myself. Think about it. If the diamonds in the Black by Brian Gavin collection are good enough for me and my son, then they're probably good enough for you. That makes sense, don't you think?
For the record, I'm not saying that Brian Gavin is the ONLY place to buy diamonds of this cut quality. The reality is that there are other diamond cutters producing some pretty spectacular looking diamonds.
Note to Brian Gavin: One of these days, I know that you're going to run across this article and call me on the phone. "Good enough? Black by Brian Gavin Diamonds are G-O-O-D-E-N-O-U-G-H?!?! Black by Brian Gavin represents the PINNACLE of my career!"
LOL. It's just an expression my friend, besides there's always the chance you could do better (he says, throwing down the gauntlet and laughing maniacally).
Where to Buy Super Ideal Cut Diamonds:
The key to being happy with the ideal or super ideal cut diamond that you buy online is to have reasonable expectations. Don't expect to get the super ideal performance of a Black by Brian Gavin Diamond out of a standard GIA Excellent cut. In my experience, that's just not going to happen.
You wouldn't buy a standard Porsche 911 non-turbo and expect it to perform like a Porsche G3, right? Of course not, that's just ridiculous. Well, diamonds are no different.
Do you want the light performance of a Black by Brian Gavin Diamond that is so incredible because it spent 4X longer on the wheel? Well then, be prepared to pay the price and don't try to cut any corners because you'll just end up being disappointed with the result.
Do you want the VERY BEST Light Performance?
Here are the best places to find H&A Diamonds:
Searching for diamonds within these collections is practically fool proof. It's true that some diamonds will exhibit better optical precision than others, but it's doubtful we will see a difference with our eyes. Still, if you want help deciding which diamond is the best of the best, you can ask for my help.
Conduct Your Own Due Diligence:
To some extent, my personal preferences for where to buy a diamond should not influence your decision where to buy an engagement ring. After all, what do I know? I only have 30+ years of experience buying diamonds at the trade level and selling them online. Why yes, that is sarcasm (thank you for noticing).
And if experience has taught me anything, it is that not everybody wants the very best every time they buy something. Some people are only going to be happy with that Porsche G3 level of performance and they will not settle for anything less.
Other people will be ecstatic driving a Porsche 911 Turbo. While other people might be thrilled to drive a standard Porsche 911 non-turbo. Or perhaps none of those options appeal to you and you would rather drive a rusty old pick-up truck. Of course, this is a diamond engagement ring that she's going to wear for life!
As you can see, those Porsche prices increase with performance class!
Of course, it is not my place to tell you what to buy or what type of light performance you should settle for. My role in this situation is to simply help you understand the differences in diamond cut quality. Then you will have the information necessary to make an informed decision and decide what level of light performance is best for your individual situation.
I view my role as being something of a tour guide with experience navigating the realm of ideal cut diamonds. As we wander through the different dimensions of cyber space, exploring the offerings of each diamond vendor, I will point out the pros and cons, and niche markets that each company specializes in serving.
I will try to answer all of the questions that come to mind and help you determine which cut class of diamond will best suit your personal needs and preferences. At the end of the day, it is up to you to decide what level of light performance and sparkle factor you desire.
It goes without saying that I personally prefer the hearts and arrows diamonds produced by Brian Gavin. After all, they used to used to produce hearts and arrows diamonds for our private label collection.
Thus, I have a lot of experience with knowing how those diamonds are going to perform. Which is not to say that other diamond cutters aren't capable of producing diamonds of the same cut quality, it's just that most don't with the same degree of consistency.
Brands that Deliver that Porsche 911 Turbo Performance:
While it certainly is possible that you might find an H&A Diamond "Cut to the Nines" that will deliver the Porsche G3 Light Performance of a Black by Brian Gavin. It's easier to find the Porsche 911 Turbo level performance of Brian Gavin Signature, or WhiteFlash ACA.
Within the inventory of these vendors, I generally find that they meet the mid-range of my grading standards for hearts and arrows. With that in mind, you should expect to find a little more variation in the consistency of the hearts and arrows pattern.
These are "Hearts & Arrows" diamonds by industry standards and they should exhibit better light return and sparkle factor than standard ideal cut diamonds.
They will also cost more than entry level ideal cut diamonds because the higher degree of optical precision demands a higher price. I generally find the production of these brands to be slightly less precise:
In that case, they sometimes cost less than their competitive counterparts. It is essential to realize that each brand has specific pros and cons. Ultimately, the ideal situation is to keep an open mind and determine which vendor has the best options available.
The best way to do this is to search all the vendors for diamonds within a specific range of characteristics and price. Then select the diamond with the cut quality and performance within the range that appeals to your sense of balance.
Shifting Down to the Standard Porsche 911 Level of Light Performance:
I used to drive a little black standard Porsche 911 non-turbo. Driving that car was a real blast! I absolutely loved it. Right up until I had the opportunity to drive a Porsche 911 Turbo and experienced the difference in performance for myself. Then a friend of mine who is a "Porsche Enthusiast" let me drive his 911 Turbo S-class and it blew the doors off my last experience.
The adage "you don't know what you don't know until you know that you don't know it" definitely applies to buying a diamond engagement ring. The time to learn about diamonds is before you buy because nothing sucks more than discovering the difference in light performance after you propose.
Imagine hearing your fiancé ask:
"Why do you think her diamond sparkles so much more than mine?"
Of course, if you buy a super ideal hearts and arrows diamond like the ones I recommend, the odds are that other people will be asking her that question. "Why does your diamond look so amazing? Where did you buy it?"
At this point, you might have read enough blog posts to feel comfortable buying a diamond sight unseen simply by the details provided on the diamond grading report.
The vast majority of people are perfectly fine with the performance level of a standard GIA Excellent or AGS Ideal cut diamond. Just as many people are perfectly happy driving around in their Porsche 911 and don't feel the need to spend more for better performance.
With that in mind, when people tell me that they want a standard GIA Excellent or AGS Ideal cut diamond, I search the following dealers and cherry pick the best options from each one:
Once the best diamonds from each vendor have been identified, you can fine tune the selection process and decide which one is right for you. Of course, if you're looking for the very best in light performance, you can skip 90% of the journey and stick with the vendors who specialize in Hearts & Arrows diamonds.