Tuesday, August 23, 2011

Jewelers Prefer Prongs. You Don’t.

Why don’t you like prongs?  I so wish you did!  Deep down, this is what I want to say whenever I get a new custom order for bezel set gems.  But I hear you.  It just looks so nice, and it’s a very protective for the stone, too.  So if we’re going to bezel set your stone, there are some things you need to know.

First of all, let’s talk about why jewelers prefer prongs.  For one, prongs can better accommodate odd stone sizes and depths.  There are no prong settings for cushion cuts, but very often a round or a square setting will work.  And most existing bezels for pears are 8x6, 7x5, and so on.  Whereas most pear shapes are fatter, shorter, or longer (i.e. 8x7, or 7x3).  But prongs can be opened up just a little, and in a 4 prong setting, the gem can stick out on both ends and that won’t matter.  You can also take a prong setting, cut some metal from the bottom half, then re-solder the wire to make a narrower setting.
Another reason why jewelers prefer prongs is because the stone is less likely to break during setting.  Paradoxically, it is the soft stones you would want to bezel set for precisely that reason.  Oh well….

So as you’re dreaming about the next bezeled ring or pendant, keep in mind a few simple rules.
1. Bezels come in standard sizes, gems don’t.   For rounds, there are full and half mm sizes; and with straight, as opposed to tapered bezels, the stone has to fit exactly.  If it’s 1/10th mm too big, it sticks out and the walls don’t fold.  If it’s 2/10th mm too small, it will fall through the back.  For ovals, pears, and emerald cuts, the easily available sizes are 5x3, 6x4 etc., but not 5x4, or 6x5.

2. There are tapered bezels and straight bezels.  The straight bezels require a nearly perfect fit, the tapered bezels can be shaved down a little from the top if the stone is too small (for a perfect fit, it should line up with the rim of the bezel).  Most tapered bezels on the market have an airline, however.  That means they are not fully closed but have an opening on the sides that goes around the stone.  This allows for more light to fall in.
Two straight bezels (an oval and a princess), a round tapered bezel with airline and a half-bezel, similar to a tourmaline setting (with a tourmaline sitting in it).
3. Not all stone shapes have bezels you can buy.  Here’s a big mystery for you: there are no cushion shaped bezels available anywhere.  Who knows why.  It is the same with baguettes.  For baguettes, you usually use prong settings or a setting (called tourmaline or baguette) that has two walls folding in on the stone on the outer ends.
4. If you buy 14K, you usually have more choices available, because in the industry, gold is still used far more than silver.  For now…
What happens if the bezel you want doesn’t exist and that you need to have it made?

There are two ways to make a bezel (that I know of).  The easy method is to use step bezel wire which has a second inner wall that will serve as the seat for the gem (look at the picture with the bezels, the way the straight bezels look gives you an idea of the shape of the wire).  This wire gets folded gently around the stone, with grooves filed on the inside to allow corners to fold in, and the ends soldered together (or if you cut three pieces for, say, a triangle, then you solder the three seams).  Making this kind of bezel takes about a half hour on average.  And: I know how to do it!

The hard method is to take a block of silver, or a block of wax if you like, and shave out the opening for the stone with a drill, then shave the outside to suit.  That’s like sculpting, essentially, just with different tools.  Like Michelangelo, you’re digging out a little cushion shaped David from a piece of metal or wax. 
This, by the way, is the only way to make a tapered bezel for an oddly shaped stone.  But I cannot do it for you.  I can hire out, I did it once for my 6mm cushion bezel.  But it cost $60 and it took the guy all afternoon.  I’m glad I did it because I had it cast to make more, but now all I have is that one size.  I can shave the top to make it smaller, but I sure can’t make it bigger. 

Ring with My Handmade Cushion Bezel
Lastly, there are three reasons for why you, too, might prefer prongs.
1. Your stone is likely to break if bezeled.  If it’s a soft stone (kyanite, sunstone, Mexican fire opal, apatite), and especially if it has sharp corners like a princess cut, forget bezeling it. 

2. Your stone is too deep.  Some stones are so deep they stick out the back of a bezel.  This is not such a big deal for a pendant, but in a ring it may be uncomfortable to wear.
3. Your stone is too dark.  Normally a bezel is recommended for medium to lighter gems because the bezel takes away the light.  Sometimes, what I do in that case is solder the bezel on top of the ring shank because the silver behind it will brighten the gem.  But if it’s a deep bezel, that won’t work.

Happy designing!

Sunday, August 7, 2011

Can You Get a Gem Like This? Some Brief Notes on Odds

I periodically get questions like these: can you get a 5mm princess cut blue tourmaline?  Or: do you have a matched pair of 4mm round Ceylon sapphires?  And sometimes that’s a “yes”.  Mostly, though, it’s tough.  To communicate how tough, let’s play a numbers game by multiplying out the possibilities. 

1.      Gemstone shapes: There are 8 basic gem shapes: round, oval, emerald, baguette, trillion, princess, cushion, pear.  There are also lots of odd shapes, most of which don’t fit into stock settings, let’s skip those.
2.      Gemstone sizes: Let’s assume that there are 10 sizes for each shape.  For instance, rounds, trilliants and squares will be 1mm, 2mm, etc, ovals and emerald cuts will be 2x1, 4x2, etc, and baguettes 6x2, 8x4, etc.  Baguettes can also be 8x3 or 8x2, and of course there are tons of in between sizes.  We’ll ignore them all.
3.      Gemstone cuts: there are tons, and they matter at least somewhat.  I.e. it matters for setting if the back of a stone is brilliant cut (shallow) or step cut (deep).  For looks, the surface matters.  Some people like checker top, for instance.  Or no facets on the top, which is called “buff cut”.  Rectangular stones are sometimes radiant cut in the back for more brilliance.  All the square cuts, which I inaccurately lumped under “princess cuts”, divide at least into square, princess, or French cut.  There are dozens of cuts out there, not counting combinations.  But let’s just say there are 2x2 relevant cuts for each gem.  That’s two for the top side, two for the bottom side, meaning 4 in total.
4.      Gemstone colors: This is difficult.  Some stones (peridot for instance) all look nearly the same, whereas others (tourmaline) almost never do.  Some colors are rare (blue and turquoise tourmaline for instance), some popular (royal blue sapphires).  For tourmaline, it would be an understatement to say there are 10 different greens, for peridot, it might be an overstatement to say there are three.  A conservative medium might be to say there are 5 different colors per gem, including shades.  I.e. sapphire might be light, medium to royal blue, midnight blue, or purple.  Fancy sapphire might be pink, yellow, orange, green, white, not including any hues.  Tourmaline might be blue, turquoise, grass, forest, and olive, excluding shades.
5.      Gemstone origins: This doesn’t always matter, but let’s restrict ourselves to when it does.  So we won’t care about amethyst, red garnet, citrine, or other quartz.  We will care about emerald, which can be Columbian, Brazilian or Zambian, for sapphire (which comes from Sri Lanka, Madagascar, Australia, Burma, Tanzania…), ruby (Burma, Afghanistan, Thai…), aqua (Brazil, African…), spessartite (Tanzanian, Kenyan, Nigerian…), tourmaline (Brazilian, African…), etc.  With these and other gems, origin matters because of color, quality, and of course, price.  I am going to settle on an average of 3 origins per gem.
6.      Quality: obviously this is very important, but the quality of a gem can range so vastly that I will exclude it.  Let’s say that in general, you want the medium to nicer stuff.

Blue Apatite and Green Zircon Mixed Shapes
Now let’s multiply the odds of finding your gem:
8 (shapes) x 10 (sizes) x 4 (cuts) x 5 (colors) x 3 (origins) = 4800 possibilities

So the odds of finding your gem are an average of 1:4800 for EACH gemstone in at least these categories: sapphire, ruby, emerald, tourmaline, spessartite, tsavorite, alexandrite (the odds will be a little less there, but of course you have to find it in the first place), aquamarine, spinel, and I don’t even know what else. 
Different Kinds of Ceylon Spinel
1.      Most gems are cut according to the shape of the rough, other cuts are uncommon (I’ve never seen a spinel or a spessartite or a tsavorite cut as a baguette).
2.      Certain stones are cut for color retention (so it is hard to find a brilliant cut Ceylon sapphire).
3.      Many gems are cut for maximum size (which is why princess cuts are hard to find).
4.      Some gems don’t exist in certain sizes, or are extremely rare (it is hard to find very small topaz, and hard to find very large alexandrites or rubies).
5.      Some origins are rare.
6.      Matched pairs make for two needles in a haystack, not one.
7.      Untreated gems (in some cases) are rare.
8.      Reminder: we totally excluded the category of quality.

All this affects the odds, mostly by way of increasing them.  The odds of finding a true padparadscha sapphire (meaning Ceylon origin and real salmon color) in a size larger than 2 carats are very small.  Recently a customer asked for a 1 carat round alexandrite of 6mm or larger.  You know what the alexandrite dealer said?  It will be 1 carat, but it isn’t going to be round.
So yes, you can keep asking me to find you certain stones.  I seem to be producing an ever increasing variety of gems (even I am surprised).  But be flexible.

A Few Different Australian Sapphires