Gem cuts?

[strmrdr]

Im relativaly new to gems but so far my favorites are rubies ,honey zircon and blue zircon.
I also like round stones what is the best cut for showing off the color of the above gems in a round shape, which would have the most fire.
step cut
diamond cut
others?

Are other shapes than round better for showing off gems?
There are several pear shaped ones I loved the looks of also.
Do you loose a lot of fire going to other shapes?

 

[Michael_E]

Hi strmrdr,
Thanks for telling me about this forum by the way.
As to your question. The best cuts for light colored stones are those which add depth. These are the portugese and the barion styles. Greater depth gives the light a longer path through the gem and increases the intensity of color. If fire is what you're after then you want a tall crown with high angles and a shorter pavilion. This causes maximum dispersion, (the spreading of light into rainbows). Just as with diamonds, there are tradeoffs, you either get maximum depth of color, maximum fire, maximum brightness or some happy medium.
One thing to remember is that as a stone gets darker in color its ability to produce ANY fire is drastically reduced because the only light left to come out of the stone is the color that you're seeing...everything else has been absorbed by the stone !

 

[strmrdr]

Your welcome

I hope you dont regret it. lol
I usualy have a ton of questions when I jump into something and it looks like im jumping into this!

Im looking into the cuts you mentioned and likely will have more questions.
Thank you :}

 

[Colored Gemstone Nut]

Michael,




It is nice to see a new face around here. It will be interesting to see the depth and insight you will provide in the colored stones section...

 

[valeria101]

Welcome to Pricescope!




Maybe I could have an old Q taken out of the way...


I know PS is all about light return and sparkle. However, I was left with the impression that these are not always the priority for colored gem cuts. Personally, I would go for as little extra under the pavilion as possible in stones which already have desirable color properties for shallower depth. For example, a long rectangular tourmaline with relatively few step or scissor cut facets is the way to go (and yes, I know that such a cut is probably due to the shape of the rough...). Of course, a long, shallow stone will leave little place for inclusions to hide and will show its body color for what it is. While the portughese cut is especially stryking, I am always left wandering how on earth to wear a large, deep stone 10mm or more above my typing/writing/knocking-on-doors finger? Ok, no such problem with smaller stones...




I am quite accustomed to go for what I want and leave market trends and fashion aside. Is dispersion (sparkle) and optically enhanced color the way to go, market-wise?

 

[Michael_E]

Thanks for the welcome everyone!
AnA,
There are two things driving the type of cut that any stone receives. One is the desire to retain the maximum amount of weight in order to get the maximum financial return. The other is to make the stone as attractive as possible in order to sell it and realize that financial return. If the shape of the rough allows it,(as is the case with a diamond), then you often lose as little as 50% of the stone when you're cutting it. With most colored stones you will lose between 65% and 80% of the stone during cutting. With a very valuable stone, say a fine blue sapphire, you will make MUCH more money by cutting it poorly and keeping as much of the weight in the finished piece as possible. In that case you will, of course, play down the fact that it's poorly cut and play up the fine, desirable color.
If a cutter really wants to do a fine job, then they absolutely have to keep the angles of the pavilion of the stone at or above the point that the stone loses the light going into it, and forms a "window". This requirement for certain angles, (typically over 40 degrees), sets the depth of a stone to a certain minimum realtive to the narrowest dimension of the stone. In simpler terms, "You can't have it both ways". If it's too shallow, it leaks.
You can get creative though. By carving "dimples" and other concave surfaces on the back of very shallow stones you can create reflective surfaces on large stones that are shallow. I've attached a pic from a site which sells "Torus" cut stones. Here's the site:
http://www.jewelryexpert.com
I hope this helps.

 

[valeria101]

Thanks!

Oh, well... with the picture attached you did stryke a weack spot! I know that the initial presentation of this cut (was it Gems and Gemology?) included non-round pieces. However, I do not know wether these are still on the market. Do you?

Almost forgot... This is just a suggestion: given that PS is a place dedicated to new and weirdly useful ways to communicate the quality of diamonds (meaning grading the cut, but also any other conceivable grades, as youmight have seen by now), I was wandering wether it would be worth to create a thread dedicated to colored stone grading. Not really commenting on each type of stone, but rather describing things like tone, saturation, clarity groups and so forth. If diamond grades are of so much interest here, maybe this could be a good place to chat (and post) about similar 'standardization' attempts for colored gems, for what they are worth.
Not that I have absolute respect for such 'grading' methods, but... it is frustrating to see the level of detail discussed for diamond grading, compared to the rest! Any thoughts?

Besides, the company which produced some of the diamond grading instruments used and showed around here, has some simmilar object in the workd to turn gems into standard info bits! I would definitely like to start a new PS chapter about such things...