HCA scores

[diamondsareagirls]

Had a day of looking at diamonds and came home and plugged in the HCA scores.

The best two are .7 and 1 so I thought both really amazing - except HCA says 0-1 not best for rings. Why is that?

The other scores were 2.6, 4.3, and 5.2 so I assume besides the 2.6 the others are too far below the cut off (honestly though they all looked sparkly to me - however I like a tool that tells me how they may perform under all different conditions).

Thank you!

 

[rockysalamander]

Yup. Lots and lots of diamonds on the market are very poorly cut.

The HCA tool is an exclusion tool. You use it to weed out poor performers. So, from those you listed, I'd leave on the .7 and 1 and kick the rest to the curb (but, if you gave us the actual angles of the 2.6 and it ended up being a 60/60 style diamond, HCA may be being a bit harsh). Then, it comes down to looking at the actual angles to determine if they will work well in a ring or not. Then, get an IS or ASET to evaluate actual light return and symmetry of the cutting.

 

[diamondsareagirls]

So the numbers are: Depth 60.7/Table 54.2/ Crown angle 34.5/Pavillion 40.6 (.7 acore)
and the other is 61/58/33.5/40.8 (the 1 score)

 

[rockysalamander]

So the numbers are: Depth 60.7/Table 54.2/ Crown angle 34.5/Pavillion 40.6

This is just fine to pursue. Can you get an IS or ASET image.
The 33.5 CA is too low for me.

 

[diamondsareagirls]

I only have the image (if this is even what you wanted!) of the one you liked.

 

[diamondsareagirls]

How bad is the angle on the other one?

 

[diamondsareagirls]

And the 2.6 is 62.5/56/35.5/40.8

 

[Octo2005]

I only have the image (if this is even what you wanted!) of the one you liked.

What a cool looking photo! Do you know what type of "testing" this was? Not an image I am used to seeing here, I can't wait to hear more about it from our experts.

Can't comment on the performance of the diamonds, as MRB's are out of my element - but I am going to guess that it is loosing light under the table, since the rainbow colors are less pronounced there.

 

[diamondsareagirls]

I am not sure what that kind of picture is called!
It's of the Eightstar (that the .7 score) and I am debating it to a local unbranded one with a 1 HCA score (but a 33.5 crown angle) that I saw in person, but don't have an image of.

Can you see inclusions in that picture or is it just for light?

 

[Lorelei]

Had a day of looking at diamonds and came home and plugged in the HCA scores.

The best two are .7 and 1 so I thought both really amazing - except HCA says 0-1 not best for rings. Why is that?

The other scores were 2.6, 4.3, and 5.2 so I assume besides the 2.6 the others are too far below the cut off (honestly though they all looked sparkly to me - however I like a tool that tells me how they may perform under all different conditions).

Thank you!

Scores below 1 on the HCA are usually shallow combos which can be preferable for pendants and earrings rather than rings, not in all cases but some. This is because an effect called obstruction can be noted where the stone looks dark under close inspection due to the shadow of the wearer's head. It's best to have such stones evaluated by an expert with the stone in hand, but this is a generalisation, some <1's can be perfectly fine for a ring.

Both sets of proportions have tremendous potential. Don't judge inclusions or lack thereof from these images by the way, your own eyes are always best. Sorry, did I miss the clarity grades?

 

[diamondsareagirls]

Does the 33.5 crown angle bother you of the one that scored a 1? They all look good to me in the store, I am a terrible judge! But I am scared of taking it out in different conditions and not having the "fire" that my current diamond has. It did score excellent fire and scintillation on the HCA tool.

I actually haven't seen the .7 score because it's an hour away. But I do love my current 8star so feel relatively confident I would also like it.

I love Whiteflash (my wedding band is a 5 stone ACA), but they won't take my trade in and selling privately seems daunting so trying to keep it local or go back to 8star.

 

[Lorelei]

Does the 33.5 crown angle bother you of the one that scored a 1? They all look good to me in the store, I am a terrible judge! But I am scared of taking it out in different conditions and not having the "fire" that my current diamond has. It did score excellent fire and scintillation on the HCA tool.

I actually haven't seen the .7 score because it's an hour away. But I do love my current 8star so feel relatively confident I would also like it.

I love Whiteflash (my wedding band is a 5 stone ACA), but they won't take my trade in and selling privately seems daunting so trying to keep it local or go back to 8star.

A 33.5 crown angle is nothing to worry about at all, especially if all the other proportions are there - and they are. If the new stone is also an 8* then I feel you have no worries whether you'll like it or not as this brand is pretty consistent from what I hear.

Also don't worry about the HCA predicting performance nuances, it can't really do that. If you can't get to see the diamond in person, see if the seller can do a video for you, that might give a better idea.

 

[Lorelei]

And the 2.6 is 62.5/56/35.5/40.8

I'd want an ASET/ Idealscope for this proportion combo for sure due to the numbers ' possibly' being problematic. It's a bit deep too.

 

[diamondsareagirls]

I think I will stick to what I know with the 8star.
The question is now whether to get a 1.26 vs 1.40 with similar stats. 2k more for the 1.40 and the differences is 7.0 vs 7.3mm. Is that going to be a big difference on a 4 1/4 finger?

 

[skypie]

Check this out to see the size difference:
https://www.diamdb.com/

I think I will stick to what I know with the 8star.
The question is now whether to get a 1.26 vs 1.40 with similar stats. 2k more for the 1.40 and the differences is 7.0 vs 7.3mm. Is that going to be a big difference on a 4 1/4 finger?

 

[Lorelei]

I think I will stick to what I know with the 8star.
The question is now whether to get a 1.26 vs 1.40 with similar stats. 2k more for the 1.40 and the differences is 7.0 vs 7.3mm. Is that going to be a big difference on a 4 1/4 finger?

I think that's a nice size difference personally.

 

[rockysalamander]

I've lost track which is the 8* and which is not, sorry, but just like any other branded cut -- the HCA or our typical proportions may not predict performance. Many of the super-ideal branded stones (ACA, HPD-CBI, 8*) have extremely high precision and that provides better optical return.

That rainbow picture is just their way of showing how much light their diamonds return. I'd rely on an Idealscope or ASET, which the IS is posted on their website. Very clean and bright.

You might reach out to GOG in terms of a trade option. They used to (still do?) sell them. That might allow you to look at the Ascendancy diamonds, which is their super-ideal.

 

[diamondsareagirls]

The 8star is .7 score on HCA. Does the rainbow image of it look ok even if not the best image to judge it? I have no idea what I am looking at.

 

[rockysalamander]

The 8star is .7 score on HCA. Does the rainbow image of it look ok even if not the best image to judge it? I have no idea what I am looking at.

I have not seen enough images in that rainbow format to make a judgement. Ask for an IS (they call it a SymmetriScope). Maybe @Wink who used to sell them can tell you how that rainbow image compares to others in the history of that stone.

 

[denverappraiser]

The rainbow image looks like a Diamond Profile image. They're not in business anymore but they were a predecessor of the ASET and maybe also the IS. It's the same general idea of a reflector but I don't remember how to interpret the colors. Whoever supplied the picture may be able to help but there's no direct translation to either ASET or IS.

 

[diamondsareagirls]

Does this help at at all with the .7 HCA score/rainbow picture? It’s an I with SI2 clarity. Dealer says eye clean. There is strong fluorescence. My other option is the 1 score I posted that is H/SI1and not an 8star or any brand. Prices are the same. llis

 

[Johnbt]

It's amazing how many pages I bookmarked in the month before I bought an engagement ring. I vaguely remembered seeing a stained glass image. So, after much searching, an article from 2005...

https://www.goodoldgold.com/red-reflector-history

Scroll to the bottom section on Kelsey McLeod for an extensive history on what started as painting the inside of half a pingpong ball.

There are 3 images shown - shallow, deep & ideal

And a caption:

"They later added more colors and divided the reflections into 4 quadrants.

White representing the 0-90° zone.

Blue representing the 90-180° zone.

Yellow representing 180-270° zone.

Red the 270-360° zone."

Then there are 3 more images.

 

[diamondsareagirls]

Thanks Johnbt. I am going to give it a go and try to figure out my picture!
Do you think I can just trust 8star is going to be a fiery diamond and not worry about SI2 and fluorescence? I just don't want to give up the one I have for a less fiery one!

 

[Dancing Fire]

Does this help at at all with the .7 HCA score/rainbow picture? It’s an I with SI2 clarity. Dealer says eye clean. There is strong fluorescence. My other option is the 1 score I posted that is H/SI1and not an 8star or any brand. Prices are the same. llis

A very well cut stone based on its specs.... GIA graded?

 

[diamondsareagirls]

No. I only have a Gcal report with my other eight star so I don't think they do them.

 

[Garry H (Cut Nut)]

The rainbow image looks like a Diamond Profile image. They're not in business anymore but they were a predecessor of the ASET and maybe also the IS. It's the same general idea of a reflector but I don't remember how to interpret the colors. Whoever supplied the picture may be able to help but there's no direct translation to either ASET or IS.

Actually Neil it is a pinhole lighting with thousands of tiny holes to let light shine on the diamond. Marty Haske used them.
i have a lighting model somewhere filed away for DiamCalc that can produce the images too.

 

[Garry H (Cut Nut)]

A very well cut stone based on its specs.... GIA graded?

See the side profile of the stone - the girdle wave is classic eightstar and is what is described as a painted crown. The minor facets are less steep than they would otherwise be. This stone will appear even darker than an unpainted diamond from close up.
Take a ruler, place it between your eyes. run your finger along and see how close you and your other half can focus. If you can focus closer than 8 or 10 inches you will find this stone dark on close inspection. Above 12 inches it will light up.

 

[diamondsareagirls]

I am doing this right now with my current 8star and don't see anything, but it's smaller! That is really scaring me! Does anyone ever look that close in real life?? How dark are we talking?

At 12 inches away will it be brighter than other diamonds like the ACA?

 

[Garry H (Cut Nut)]

Younger people can focus closer, and when they are shopping for expensive Erings they look very closely.
The rest of the time I think most people like slightly shallower diamonds.
Most of the industry disagree with me.
8* are usually I think a little deeper / steeper than the one on offer.
8* have less edge leakage which mased them look a little larger but reduces some edge contrast / flashing effects.