Preferences between HCA Holloway Cut Advisor Scores?

[Toska]

I noticed a comment on the side of the HCA http://www.pricescope.com/cutadviser.asp which says...

"A score below 2 (Excellent) means you have eliminated known poor performers (more than 95% of all diamonds). Your own personal preference may be for a diamond with an HCA score of 1.5 more rather than one with a lower score of say 0.5."


Can Garry Holloway, or someone else tell me why a person would prefer a diamond with a score of 1.5 over a diamond which scores 0.5
I thought the lower the score, the better the diamond is? Would a 1.5 be much different to a 1? a 1 much different to a 2?

 

[aljdewey]

 

[magna2]

Some people like brilliance over fire and vice versa. A HCA score of 0.5 does not equate to a better performaer than a score of 1.5. Thus depending on your personal preferences, you might prefer something that is more fiery or something more brilliant.

 

[Mara]

Yes it definitely has to do with personal preferences. I also remember reading that diamonds which score very low, say around .4 TIC, are not always as attractive, though I can't remember who I heard that from or why.

 

[Toska]

What would a diamond with a 1.3 on the HCA scale look like? I know it would not reflect as much light as a 0.5 HCA, would it show more "fire" colours?

 

[Garry H (Cut Nut)]

There are many different looks that could all have HCA 1.3.
40.9P 34.5C, 41.4P 30C and 40.2P 37.3C.
They all look different and they all look good - but some will prefer one over the other.

 

[Toska]

What would this stone look like Garry?

Size: 1.02 ct
Color: G
Clarity: SI1
Measurements: 6.54 - 6.57 x 3.88
Roundness: 0.5%
Total Depth: 59.2%
Table Size: 59.7%
Crown Angle: 33.5
Pavilion Angle:40.7
Culet: 0.8%
Polish: Excellent
Symmetry: Excellent

 

[Garry H (Cut Nut)]

Dark from close up - bright from a distance.
You have seen the stone - why are you asking all the questions Toska?

We are here to help consumers, but once someone knows what they need to know, there is not much need for us to help further.

What do you want to know that you do not already know?

BTW for those reading this thread, the vendor who sold the stone to Toska has a full blown DiamCalc.

 

[Toska]

Garry, I am asking all of these questions to receive some feedback from the professionals on this forum. Yes I have seen the stone, but I would like to know how it matches up against these super duper 0.5 HCA scale diamonds, I would like to know what it would look like next to them.

You ask what do I need to know that I already do not know? Well you just answered my question Garry, I wanted to know what the stone looks like from someone with your credentials. Thank you for the response. My girlfriend is more interested in a diamond which flashes rainbow colours than the most light reflective. I hope I have made the right choice.

The vendor which I bought my diamond from is supplying a diamcalc report by the way. I won't get my hands on it for a couple of weeks when I pick up the diamond/ring.

 

[pqcollectibles]

My diamond has a 1.4 TIC rating. Up close, mine appears clear. Some people ASSUME it is a synthetic or crystal and not a diamond. Many people think it is a 1 carat when it is actually a 3/4 carat. Mine flashes plenty of white light, but also sparks the colors of the rainbow. I too like the blasts of colored light. Performance depends on lighting.

Hope this helps!

 

[Toska]

Thank you for your comments pqcollectibles. It is very easy to get technical complicated answers on these forums, but as far as simple explanations go, it's very hard to find. I must point out that Garry Holloway provided a simple explanation of the diamond looking dark up close and sparkling from far away.

Have you found this to be the case pqcollectibles?

 

[Mara]

From what I can tell, Toska, that stone you posted about seems to be a bit on the shallow side...hence how I interpreted Garry's comment about dark up close and bright far away. Possibly like my stone, shallower crown angle...which means more light reflective *white* light rather than colored light. I don't get alot of colored light in my stone, it looks more white bright alot of the time. In certain lights I get colors but not as if it was fiery. But my stone is much more shallow than yours.




If however the crown angle was 35 and the pav angle shallower, then you'd probably have more fire than white light. However, the other #'s could change too (table and depth), smaller table probably...more around 55%? Smaller tables mixed with certain angles tend to produce more fire...larger tables mostly are more white (like mine). Or with your table/depth combo and 35 crown angle, it would still be great on the HCA--but not as great white light return. You got all EX's...thats great!




What Garry noted was that a 1.3 score may come from many different combos of pav and crown angles, table and depth numbers. A stone may score 1.3 but be shallower like the one you bought. Meaning most likely more white light. Or it may score 1.3 and be more fiery--with a steeper crown angle and smaller table. Both can score 1.3. It just depends on the numbers. Each stone will perform differently.




It's really all about preferences. I love my white light stone but sometimes wish it was more fiery. It won't be the last diamond I have though.

 

[Toska]

Mara, the HCA scores suggest the diamond has more fire and scintillation than light return. Wouldn't that mean less white light?


Light Return Very Good
Fire Excellent
Scintillation Excellent
Spread Excellent
Total Visual Performance 1.3 - Excellent - within TIC range


It scores an excellent in every category but light return

 

[fire&ice]

In the simplest of terms, the diamond looks great on paper. Don't worry. Be happy.

 

[Mara]

Toska--yes in fact it would suggest that...I had always read that shallower crown angles and slightly more shallow depth meant more white light. Not too sure...maybe an expert can pipe in.




To answer your PM, my stone's specs are as follows:




Table: 61.4%


Depth: 56.9%


Crown Angle: 29.9


Pav Angle: 41.1




My stone is very shallow...hence the large table, very shallow depth, very shallow crown angle. The pav angle compensates for the very shallow crown angle. My stone is nowhere near as shallow as yours...but a crown angle under 34 is considered more shallow than normal from what I know. Also your depth is less than your table, even if by a smidge. So your stone will look a little larger than a 1c (note your diameter) but I think you will end up trading off a bit of fire for white light return. The differences may be slight...only your eyes will tell.




The numbers are nowhere near bad..don't get me wrong, HCA gives it an excellent score and EX across the board does not come around for every stone. But when you noted your girl loves fire over white brilliance, a little alarm bell went off. This stone should be stunningly beautiful--but it may not be AS FIERY as you would assume, from what I can tell on the numbers.




An expert think otherwise?