Colored stones and depth

[Slykat12]

Now I have been a good girl and read winks stuff on colored stones more than twice and I have a couple gem books as well AND I searched the ps board for depth and got 10 million returns so here I am in search of a reasonable answer.

I am presently looking at colored stones that are cut so deep that they show up noticably smaller. I know cutters do that to retain weight and I guess I can deal with paying for stone I can't see BUT is this deep gonna effect the light return as I am looking at very sparkly like gems that are known for returning light. Thus will these deep stones show less beauty and light return like diamonds do? At what percentage should the line be drawn for a round colored stone?
Thanky

 

[belle]

there aren''t going to be many stones that scintillate like diamonds.
don''t worry about depth. you have to go with your eyes when picking a stone. finding appealing stones without windows will be your biggest challenge.

what are you after now?

 

[Slykat12]

The demantoids are .65 carats and only 5.2 mm!!!! I have not seen them yet. But I am concerned as they should be 5.6 mm. I thought they did return light like diamonds. They must be cut super deep!!!

 

[bar01]

According to at least one of the colored stone books I have - 65% is a nice target, but anywhere from 60-80% is mentioned as good range.

 

[belle]

Date: 3/2/2006 10:44:29 PM
Author: Kimberly
The demantoids are .65 carats and only 5.2 mm!!!! I have not seen them yet. But I am concerned as they should be 5.6 mm. I thought they did return light like diamonds.

ooohhhhh....purrrrrfect size for earrings!

i said there wouldn''t be too many stones that scintillate like diamonds, but demantoids are your best bet. they are usually quite brilliant and the name literally means ''diamond like''

 

[Slykat12]

Well then my question stands. As they return light like diamonds should the depth be like 60% for the demantoids?
Or am I worrying too much again. )

 

[strmrdr]

would you believe that there are over 2000 different faceting arangements for round cut gemstones?

Without knowing which one its cut with its hard to say.

usualy light material is cut deep to darken it and dark material is cut shallow to lighten it.

Diamond cut is not a great cut for a lot of gemstone material so it is likely one of the other 2000+ round cut styles.

 

[valeria101]

As far as I know...

Assuming the stones are cut as round brilliants... still the brightest proportions may not make sense- for once the 'dark' pattern accepted for diamonds (the arrows as they were, or anything else black under the proverbial Ideal Scope) is called 'extinction' on this forum and not a good thing because it impedes color. And to get rid of that (in either diamonds or anything else) without loosing brilliance you need a deeper cut... for all the good reasons.

For demantoid in particular - no, they don't have quite as high refraction index as diamonds. Better than sapphire, but less then diamond. Demantoid has higher dispersion than diamond - but you would need colorless demantoid to appreciate that. And while very washed out stones do exist, I wouldn't wish for them in particular: not nice, and very unusual.

I don't know the numbers by heart, but there's another thing that dictates how large gems look for their weight - good ol' density: the higher density, the smaller things look for any given weight... of course. Wonder if that plays out between diamond and dems? Gotta look up.

Besides, there are enough diamonds out there to shave some up & waste material on geeky cut. With vastly smaller quantities of fine colored rough to waste... Especially if cutting weight does not improve appearance. Perhaps it is obvious what to do with a badly windowed stone, or a dark one... but what if the 'heavy' cut is not bad after all? With fancy non-standardized cuts, the lines are quite blurred. Hopefully no one will get to impose (roughly) two cut models for colored stones too. Guess not... unless there will be some mass marketing campaign for the couple buckets of demantoid out there.

My 2c - somewhat biased.

'Road-kill' style cut is most of the time discounted, leaving the buyer a real option to have the thing trimmed. Perhaps not all sellers do this, but many do. Well, at least for the clearly odd, nasty stuff.

IMO, you've got some winners there!

Someone might wake up one day and produce optimized RBC models for one color or another. Not only I am not nearly expert enough for that, the exercise is against my religion too

 

[movie zombie]

and you are worrying too much! wait till you see them....see if the ''speak'' to you. these are not diamonds and should not beheld to the same criteria.

movie zombie

ps can''t wait to see them!

 

[colorchange]

Depth will depend on cut, I have one round diamond cut sapphire (lilac, Burma) that is 1.1 Ct and 6.5 mm so extremely thin but not windowed, to me it''s worth almost as much as if it were 1.6 Ct because it looks almost the same so the best way to get a good gem is to look at it...

Take care with very small ones by the way !