Gems on Photo: 1. Precision-Cut 2. Danburite

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Gems on Photo: 1. Precision-Cut 2. Danburite

Post#1 @ 11-05-11 , 11:13 AM

I have continued my section "How to judge gemstones on the internet" with two more entries:
(This is the text-only version. The original contains sample-photos but I am not sure if I am allowed to post them here)

1. Precision cut: Must be perfect on photo

Precision cut gems look terrific on photo. If they don't look perfect they probably are not. To say that any precise cut gem will look great may be far fetched, but that is the direction it goes.

A perfect cut will mask gray, strengthen weak colors, cover-up inclusions and make even black-outs look sophisticated.

You have to be aware that, as far as material value goes, a pale included gem is still a pale included gem even if it is precision cut and thus looks very sweet on photo. Of course, the pale included gem will actually also look better in person than the same gem cut badly, but it still needs to be significantly cheaper than a top-end stone.

If you enjoy a good cut expect to pay precision mark-up but don't buy lesser quality at top rates just because of an exciting looking photo (unless perhaps there is an award-winning star-cutter or an artist involved).

Note: High-end gemstones in precision cut must look absolutely perfect on photo.

You can not be too critical here (but you will need a healthy budget). The best gems of each class get their first cut close to the mines and not many gems are, or can be, re-cut into perfection later.

Precision cutting needs size and availability; both are rare attributes at the top.

What constitutes a precision cut?
- Facets are exact and meet in one place
- Symmetry and order in every dimension
- Flawless polish
- Maximized brilliancy

A pro-cutter can add many more topics but these are the basics and they should be visible on any image.

2. Danburite: Poor Show

Danburites do not compute well on photos. They are unforgiving with inclusions, tend to catch even the faintest background color, display windows merciless and are a generally ungrateful lot on photo. Even the cleanest Danburite tends to display a grainy greasiness which, though invisible to the eye, points to a unique crystal structure different from topaz.

A Danburite that looks good on an un-doctored photo is probably a beauty in person. If you have a good eye you may make a snatch with a photo-shy Danburite that will be much nicer in person.

This said, Danburite has a relatively low refractive index and will not easily sparkle as much as you would wish in a colorless gem. Optimized for brilliancy they will shine but not disperse light as diamond or, to some extend, white sapphire do.

With not much color and little luster to show, Danburites rely on good cutting. Big and clean Danburites from South-America have thus been a boon for western cutters.

So far we have not heard of any treatment in Danburite. If they come treated they will probably be diffused into some unnaturally intense color and easy to spot.

Thanks for reading. Feed-back is welcome.

Next I will work on Alexandrite and Paraiba-like tourmaline.

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