Monday, September 27, 2010

On Cutting a Stone: Chronicles of a Tsavorite

Some of my fellow jewelers have been asked if they cut their own stones.  And a friend of mine once wondered if all the stones I buy are cut specifically for me.  The answer to both questions is “no.”  For one, becoming a lapidary – a stone cutter – takes a lot of practice, and gemstone cutting is best left to those who specialize in it.  Secondly, cutting takes a lot of time (and hence money).  A tiny 1mm diamond, for instance, can take an hour to cut.  No wonder, therefore, that most small stones are not cut in the U.S.  A small amethyst, for instance, can wholesale for just a few dollars.  Meanwhile, a good N.Y. lapidary can charge $50 an hour or more for his skill.  Most of the stone I own, therefore, are cut in India, where this is an old family trade.

This raises a lot of issues about ethics and economics, doesn’t it?  Yes, we all profit from cheap labor.  There are no two ways about it.  The only mitigating factor is that the wage a cutter gets in India – which is about $1.00 per stone – buys you a lot more there than it buys you here.

Does it ever make sense, then, to have a stone cut in N.Y.?  That’s a “yes” if it is a larger diamond. N.Y. has some of the very best diamond cutters in the world.  It is also worth re-cutting a stone for repairs.  Lastly, it is worth doing, and even cost effective, when the stone is large or rare.  If you know how to pick from rough (ok, that’s not easy), or if a gemstone dealer who has rough is kind enough to pick a good piece for you, you can have it cut to your specifications, and you may find yourself the owner of a unique gem that nobody else has.

Speaking of kind persons, my gemstone dealer D., who is also a lapidary artist, picked out a beautiful clean piece from his tsavorite rough for a little demo.  As those of you who follow my Etsy listings know, it’s been very hard for me to get tsavorite.  D. only has rough, and would have to ship it to India to have it cut, which would take months.  I’ve seen other parcels on the street, but they’re prohibitive in cost.  I know of one dealer in Jersey who has his own rough cut in India (rather than purchasing finished stones), and he occasionally has small parcels of tsavorite.  I’ve bought some from him at a show last spring but sold it immediately.  I bought a matched pair at a later show but my setter lost one (yep, it happens).  I’ve emailed the dealer without much success (“we don’t have any right now,” “we’ll ship soon,” “we’ll be in touch”).  Sigh. 

Tsavorite comes only out of Tanzania and Kenya, where it was discovered in the early1970s, and because it has a wonderful true green color that occurs naturally, it is very popular among those who know about it.  It comes mainly in small sizes, so anything over 1ct goes at a premium, and only a tiny percentage of stones are over 2 ct.  The dark greens with a small percentage of blue are insanely expensive, the grassier greens are cheaper.  Tsavorite is tougher than emerald, and crisper in appearance.  I love this stone.

Now let’s get to the cutting.  Below is a picture of the piece of rough that D. selected.  This is a nice clean piece of a medium to dark forest green with an initial weight of 1.52 ct.  According to D., its initial shape suggests to make it an emerald cut, and since we didn’t have any particular plan for the piece, we went with what was best for the stone (and what would preserve the most weight).

The next picture is of the first cut, where D. pressed the stone against the cutting wheel from all sides with his finger, thus chopping off the edges and creating the basic emerald shape.  The rough went down to 1.31 ct in the process, which is a very small loss.  You can lose up to 80% of your rough in the cutting process.

So here’s a picture of stage two.

Before having to put it on a stick to cut the finer facets, D. was able to shape the rough down one more time.  This time, the stone went down to 1.06 ct.  Interestingly, that is what D. predicted.  His guess is that the stone will be about 1 ct when he’s done.  D. then polished one side of the stone with diamond powder so you can see that it will come out clean.  Here’s a picture.

And that’s where we are at this point.  The finer facets will take longer, and D. has some other cutting orders (8 emeralds for a special order), so I have to wait.  I hope to see the final product in a couple of weeks.  The stone could also break in the process, however.  But if it doesn’t, this is going to be a very fine gem. 

Monday, September 20, 2010

I like this color – what’s my gem?

I know a lot of us women (and some men, even) strive to be color coordinated.  And this puts certain demands on jewelry.  It had better match!  For this reason, and because we all have our favorite colors, I’ve been asked to supply a list of available gemstones by color.  So here’s my shortlist, together with some brief observations about each stone:

1. Garnet: deep red to pinkish red to pink, the dark reds can look sooty at night; look for shallow cuts to get good color
2. Ruby: pigeon blood red (rare, very expensive) to pinkish red, if too pinkish then its pink sapphire (the line can be fuzzy, the price won’t be, ruby costs way more than pink sapphire)
3. Fire Opal: will mostly tend towards orange color, tomato red is available but tough to find
4. Spinel: true red to pink but also available in blues and purples, the red is the most expensive

Burma Spinel, Red

Pink, Pinkish Red
1. Tourmaline: deep to light raspberry colors, sometimes light rose pink
2. Pink Sapphire: very similar to pink tourmaline, so beware
3. Rose Quartz: very light rose pink, can look extremely washed out in small sizes
4. Garnet: the rubellite version is pinkish and looks very much like pink tourmaline also

1. Amethyst: I guess you know what that looks like
2. Iolite: more indigo, think “blue jeans”
3. Spinel: various shades of pink to purplish pink, sometimes orange pink
4. Tanzanite: light lavender to dark lavender, almost all of it is heated
5. Sapphire: light to dark lavender with a lot of blue, hard to find, very expensive but gorgeous

Natural Purple Ceylon Sapphire

Orange-Red, Orange
1. Fire Opal: red to orange to yellow, almost always has a milky appearance
2. Tanzanian Sapphire: occasionally with pink overtones, mostly heated to obtain color
3. Spessartite (Mandarin) garnet: rich medium orange color, sometimes brownish (less desirable), often lightly included
4. Precious (Imperial) Topaz: pinkish orange, hard to find
5. Padparadscha Sapphire (natural): fuhgettaboutit

1. Citrine: warm yellow to brown tones, but its mostly heated amethyst
2. Lemon quartz: that’s heated quartz, very light and washed out, blah looking
3. Yellow Beryl: belongs with aqua and emerald, mostly sunflower red and slightly satiny in appearance
4. Chrysoberyl: belongs with alexandrite despite the name, has a crisper and more lemony appearance than yellow beryl
5. Sapphire: warmer yellow tones, sometimes with pink in them, often heated Tanzanian
6. Ceylon sapphire: lighter yellow to sunflower yellow, sometimes with hints of vanilla
7. Fire opal: see above

1. Sapphire: see my September blog entry on sapphire, and some pics; comes in anything from light blue to royal blue to cornflower blow to greenish blue
2. Kyanite: not expensive but hard to find faceted; royal blue, sometimes streaky looking
3. Tourmaline: the blues are mostly indicolite, and always with secondary hues of green
4. Aquamarine: very light pastel blue, often washed out, with minimal overtones of green
5. Blue Topaz: the Swiss and London blue topaz are heated and irradiated, natural blue topaz is very light powder blue without green in it
6. Zircon: think aquamarine but with more sparkle, more color intensity, and a touch more secondary hues of green
7. Spinel: mostly grayish blue, with a lot of sparkle

Blue-Green and Turqoise
1. Paraiba Tourmaline: awesome turquoise color but only for the rich
2. Tourmaline: ranges from turquoise to greenish blue to bluish green to forest and olive; almost any blue-green and green is available
3. Apatite: turquoise (but also available in greenish tones), great alternative to Paraiba tourmaline, but softer to work with

1. Peridot: grass with olives, always with secondary hues of yellow
2. Emerald: true green, sometimes with more blue in it, sometimes washed out, the most desirable color being grassy green with a tiny touch of blue
3. Tourmaline: chrome and forest greens are the nicest colors here, but olive greens are also available at a lower price
4. Tsavorite Garnet: another true shade of green, but livelier and more brilliant than emerald; grassy green but no olives, the darker colors are the most desirable
5. Chrome Diopside: dark grassy green, easy to confuse with tsavorite, but with a hair more yellow in it
6. Green Amethyst: that is heated amethyst, looks very washed out and fades over time; not recommended

Tsavorite Garnet

1. Natural topaz: very light brown with pinkish overtones
2. Brown Zircon: rich medium brown with honey
3. Smoky Quartz: the name says it.  (Smoky topaz = smoky quartz)

Refuses to be Pinned Down
1. Alexandrite: bluish green by day, reddish green by night, sometimes also purplish
2. Color Change Garnet: greenish brown to reddish pink
3. Andalusite: mostly brown but with green and pink secondary hues, depending on the light
4. Labradorite: dark background, iridescent with mostly blues and greens
5. Moonstone: light background, iridescent with blues, some greens
6. Opal: clear with lots of play of any color (= very pricey) to milky white with little play of any color (much less expensive); beware of doublets or triplets (opal glued to a dark background)

Alexandrite from India

And that’s not the end of it, but it will do.

Monday, September 13, 2010

A word about natural gemstones

So I practically got yelled at. This was by a gemstone dealer at a jewelry show last spring, in response to my question about his tourmalines. “All stones are natural. Heated is not the same as treated.”

I had asked if the stones were heated, and that is a legitimate question to ask about tourmalines. Some tourmalines are heated and some aren’t, which affects the price.

Why, then, did my question inspire such an outburst? The dealer was right in two ways, wrong in another way. He was right to say that all gemstones are natural. That claim simply means that the stone is not synthetic. “Natural,” in the gemstone business, means more or less what it means when it comes to poultry. All poultry is natural, what else would it be? It just may not be free range or organic.

The dealer was also right if his claim simply was that most gemstones are heated (especially the “precious stones”), and that this is both common and acceptable practice. As opposed to glass filling, diffusing, dyeing, or surface coating, for example.

But of course, heat treatment is a treatment! Stones are heated for several reasons: heat treatment can change color, it can intensify color, it can lighten color, and it can improve clarity. Sapphires, rubies, aquamarines, tanzanite and many amethyst, for instance, are typically heated. Almost all blue topaz are heated. Heat treatment makes more material available to the mass market, which in turn lowers the price.

If you want a completely unadulterated stone, you have to ask very precise questions, and you have to be able to trust your source. Untreated stones don’t always have the same brilliance as heated stones (sapphires and rubies are a good example), and more inclusions are visible. Evidence of heat treatment is hard to detect, and even many jewelers won’t know how their stones have been treated. So when you buy jewelry, you have two options: you can assume the stones were heated and not worry about it, or you can ask directly about heat treatment. If the seller doesn’t know or tries to fudge the answer, assume that’s a “yes”.

Untreated Aquamarine (1.91 cts) with Visisble Inclusion

To me, aside from the fact that I love the natural beauty of things, it is the chase for the untreated stone that appeals. Here’s a quote from Matlins’ and Bonnano’s Jewelry & Gems: The Buying Guide, that explains my sentiment: “Especially fine natural gemstones are rare and more costly than ever before. This scarcity has affected what is available in jewelry stores, and the choices available to consumers. Natural emeralds, rubies, and sapphires – that is, gems not subjected to any type of artificial treatment or enhancement-have never been rarer than they are today. While they can still be found, locating a natural gem in a particular size can take months of intensive searching, and when found, commands a price prohibitive to all but the most serious collector or connoisseur.” (P. xiv) The authors then give the example of a natural emerald of over 3 carats that took them months to find and fetched a price of $100,000, wholesale.

Untreated Columbian Emerald, .82 cts

Natural gems, even precious ones, don’t have to be quite that expensive. The issue here, as with so many things, is size. Stay under a carat, under ¼ carat even, and you have something much more affordable. If you have a source you can trust. And that may be the hard part.

Sandblasted Ring with 2mm Untreated Burma Rubies

Monday, September 6, 2010

From Kashmir to Tanzania: How to Pick a Sapphire

September is sapphire month, and although I personally think that birthstone jewelry is just a sales trick, I will start my September blog entries by sharing what I know about this blue gem.

Sapphires come from all over the world, but some countries of origin are much more highly prized than others. The most valuable is a Kashmir. I’ve never seen one myself, nor has anyone I know. That’s how rare they are. The mining of Kashmir sapphires is pretty much finished as far as I know, so all that’s left are collector’s items that are not in circulation.

In more or less the order of value, here are the other main sources for sapphire: Burma (Myanmar), Ceylon (Sri Lanka), Thailand, Australia, Tanzania. Burmese sapphires have a rich, medium dark royal blue color; they look a little like kyanite. Burmas are by far the most expensive sapphires on the market today, and are hard to get. Below is a picture of my unheated Burma sapphires here. If you want a pair like that, figure on $250 just for the stones. That gives you an idea. The Burmas I can get come from old stock – they are old mine, in dealer’s lingo. They were cut a long time ago.

Burma Sapphires

Ceylon sapphires are mostly lighter, and they often have zoning when you turn them over. Zoning means uneven distribution of color with lighter and darker tones (zoning seen from the back is acceptable, so long as it isn’t obvious from the front – Ceylon sapphires often have darker and lighter spots so they have to be cut with the dark part in the culet for it to make the whole stone look blue). Some Ceylon sapphires are purplish blue, and these often go at a premium. Since they are lighter, Ceylon sapphires are generally cut with a lot of depth, which adds to the weight, and thus the price. Here's a picture of a small suite of Ceylons so you can get an idea.

Ceylon Sapphire Suite

Thai sapphires are very dark blue, and have to be cut shallow so they don’t look too black. Australian sapphires, meanwhile, have a greenish tint. Turn the stone over to see the tint, or put it next to a Ceylon, then you see it right away (see the picture below, small Ceylons are on the left, Australian in the middle and the right). Australian sapphires can also be very dark and are often cut shallow. Another advantage of a shallow stone is that it is easier to set and find settings for. Deeply cut stones are hard to work with.

Ceylon and Australian Sapphire Pairs

Tanzanian sapphires are mostly a grayish blue. Tanzania is more known for fancy (or multi) color sapphires, but as of late, lots of blues have been coming out of Tanzania as well.  I have a pair of trilliant cut earrings listed, you can have a look on my etsy.

Sapphire prices also depend on clarity and size, of course. Sapphires should never be as included as rubies or emeralds, but if you want an unheated stone, which will go at a premium, you may see more inclusions and less brilliance.

A couple of weeks back, I had the pleasure of sifting through a parcel of unheated and a parcel of heated Ceylons that were between 1 and 3 carats. Normally I would not have been privy to this because it involved a transaction between two dealers, and gemstone dealers are very secretive about whom they buy their stones from. When a dealer approaches the booth of another dealer, he tries to do this when there are no customers, or he’ll be asked to return at the end of the day. Well, it was the end of the day and I was still there, so the dealers agreed I could stay and look, as well as be offered the same prices. That said, I still couldn’t really afford anything in these parcels. But I learned something very valuable: side by side, most of the heated stones looked very glitzy and clean, many of the unheated stones seemed a little duller. I saw a few amazing pieces though, among them a 1 carat deep cut yellow Ceylon and a 3 carat blue one that was just stunning. I probably should have bought it for myself. (But I always feel like buying things for myself).

What, then, is the big deal about a sapphire’s being heated? Well, mostly it’s not a big deal, it is mainly about personal preference. I have access to unheated stones, and I love knowing that their beauty is as nature intended. You should know, however, that 90% or more of sapphires on the market are heated. If you own sapphire, it is probably heated. Stones are heated to improve color intensity and clarity. According to Newman’s Gemstone Buying Guide (a valuable resource), you should assume that any sapphire you buy is heated. And if you ask a gemstone dealer if his sapphire is heated, he will probably act offended, saying “yes of course, they are all heated,” so as not to diminish the value of his merchandise.

I cannot personally tell if a stone has been heated, but the rule is that if you ask a dealer about heat treatment he must answer you honestly. Also, if the stone is unheated, the dealer will probably tell you this because it is an extra selling point, as well as a justification for a higher price. Lastly, any gemstone dealer who specializes in sapphire should be able to detect evidence of heat treatment under magnification.

On occasion, sapphires are also fracture filled or diffused. Diffusion treatments are common for star sapphires, for instance, because it brings out the star. Unfortunately, it turns the star sapphire grayish. I don’t recommend diffusion treated stones, and fracture filling is also not an acceptable treatment. Heat treatment is the only acceptable treatment for faceted sapphire.