I got the following question from two customers just this
week: can I supply a matched pair of Merelani mint garnets, elongated pear shape. The answer – and I don’t even have to look –
is “no.” (I actually did find one pair,
so I was wrong, but you’ll see the astronomical price tag on my Etsy site!)
So why doesn’t any gem come in any cut? The answer is really simple. Gems are cut to maximize the rough. Take, for instance, tourmaline rough, which
is cylindrical and long. That’s great
for elongated pear shapes. So is aqua
and emerald sometimes (all three are beryl so the rough is very similar). But most garnet rough is more roundish,
pebble like. That’s why it gets cut into
ovals, some rounds, cushions, and anything else that accommodates that
shape.
Also, certain cuts bring out the beauty of the material,
hence the famous “emerald” cut. Emeralds
are more sleepy than crisp, so an emerald cut, which has fewer facets, can
bring out the color over the clarity.
Ceylon sapphires, by contrast, are usually cut into cushions and ovals,
with step facets in the back. Step cuts
are bulkier but for Ceylon sapphires this is important because the color is
sometimes just in the culet, and that cutting will create the illusion of an
even tone when the gem is viewed from the front. This explains the famous “zoning” that you
can often see from the back (so it’s ok if you see it) but not the front (so it’s
not ok if you see it). Tourmalines that
have watermelon coloring (pink inside, green at the rim) are often sliced or
carved so that this effect is preserved.
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| Dravite Tourmaline Rough and Cut (Ovals are Best) |
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| Diopside Rough |
Some gems, i.e. amethyst, come in just about any shape. That’s because amethyst is so cheap it can be
bought by the kilo. It then doesn’t
matter how much you waste, most of the cost is in the cutting anyway. The material is (nearly enough) free. In other cases, i.e. tourmaline these days,
the rough is very expensive. And of
course, when you buy and re-sell, your calculations are based on your cost. If a customer wants you to do a special cut that
wastes the material, your cost is still the same and so you will charge more
for a smaller gem.
This also explains why despite what is commonly claimed, a
retail customer does not necessarily lose out when she buys a stone that is cut
to preserve weight. Because if the
seller marks up based on the cost of the rough, the buyer can get the most
amount of weight – and hence value - out of her purchase. Of course many sellers do not have a straightforward
markup policy, they charge what the market will bear. In that case the customer can lose out if
she hasn’t looked at the prices of the gem she wants to buy (comparison
shopping really pays in these cases). That’s
why it always pays for you as a customer to have some idea of the current
market, of the most common cuts for gems, and for what is and isn’t possible based
on the rough. A few minutes of internet
browsing of some of the common gem sites is usually enough to get a basic idea.
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| Burma Spinel Rough Crystal |
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| Kyanite Rough, Just Shaved Around the Edges |
Here are some of the most common cuts for popular gems:
Amethyst: cheap rough, any cut.
Alexandrite: elongated cushion, oval. Round costs extra.
Aqua: any cut really, the rough is a nice size.
Citrine: cheap rough, any cut.
Emerald: Emerald cut and oval, some pears, rounds are at a premium.
Rhodolite garnet: any cut.
Ruby: Elongated cushions, ovals, then rounds (same as sapphire)
Sapphire: Elongated ushions, ovals, then rounds. Very few pears. Step cuts for Ceylon.
Sphene: Ovals and Elongated cushions, then pears. Very few rounds.
Spinel: Cushion (square and elongated), oval, then round and pear.
Tanzanite: Lots of ovals and rounds, some cushions. The rough is a bit bigger so more shapes are possible.
Tourmaline: Lots of longish cuts including emerald cut and pear shapes, not many rounds.
Tsavorite and Mint Garnet: Ovals, then all the other cuts.
Alexandrite: elongated cushion, oval. Round costs extra.
Aqua: any cut really, the rough is a nice size.
Citrine: cheap rough, any cut.
Emerald: Emerald cut and oval, some pears, rounds are at a premium.
Rhodolite garnet: any cut.
Ruby: Elongated cushions, ovals, then rounds (same as sapphire)
Sapphire: Elongated ushions, ovals, then rounds. Very few pears. Step cuts for Ceylon.
Sphene: Ovals and Elongated cushions, then pears. Very few rounds.
Spinel: Cushion (square and elongated), oval, then round and pear.
Tanzanite: Lots of ovals and rounds, some cushions. The rough is a bit bigger so more shapes are possible.
Tourmaline: Lots of longish cuts including emerald cut and pear shapes, not many rounds.
Tsavorite and Mint Garnet: Ovals, then all the other cuts.
A good rule of thumb is that oval is the cheapest and most
common cut in most stones. Round is the most expensive.
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| Watermelon Tourmaline Slices |
