Saturday, August 25, 2012

Gem Grades

Recently a friend showed me some stones that were in nice little gem jars and had an official-looking 'Certificate of Authenticity' accompanying them. They happened to be rubies, about 7-9 carats each, and they were appraised on the 'certificate' for over $1000. They had been given to her from a family member, passed down, and were certainly NOT worth anywhere close to that amount. 

It got me thinking, that just because a gem is called a 'ruby', or 'emerald', 'sapphire' or even diamond for that matter, doesn't mean it has unlimited value. Most of you out there who are jewelry-makers already know this stuff, but the average person probably doesn't, and it's up to us to let them know the truth before they get swindled. (Or at least, before they think they're sitting on a gold mine of precious gems....)

So for you average person out there, who loves gems but doesn't know much beyond that, let me tell you, there are various factors used in the industry to 'grade' gemstones. Most of us know all about the diamond rating system, but colored gemstones also have categories of grading.

You may have a ruby, but you may not have a gem-quality ruby.

So let's go through some of the factors, using the pics below of my current ruby stock (question: what is the most valuable stone below and how much is it worth? answer at end of post)

Also, take a look at the GIA (Gemological Institute of America) website for more information about stones:

Here's a collection of rubies- the small faceted ones on the right are 4mm round and the faceted ones on the left about 7mm round. That should give you some idea of size. That leads us into our first category- size. Obviously, a larger gem is more valuable and rare than a smaller one. That said, not everyone wants a 25-carat ruby on their finger. Each person has individual tastes and for some, bigger is not better. Still, generally a larger sized stone will be worth more than a smaller stone per carat. So, does this mean the large rectangular stone is worth the most?

The next category is color. This includes hue (red, green, blue, etc...), saturation and tone (light to dark). In general, rich bright colors rate a higher price. So, for some, a deep dark amethyst is the cat's meow. But for others, they don't like the darker purples; they like the lighter purple. Again, some allowance for personal preference here. But if you look at the above stones, do you see some that are brighter and more color-saturated than the rest?

The next category is clarity. This is basically the same as inclusions. The clearer a stone is, with the least visible inclusions in the stone, the more valuable it is. In the above pic, which stone(s) fits that definition? Did you know that emeralds are almost never free of inclusions? They and tourmalines fit the category of stones nearly never inclusion-free. There are, of course, some stones that are almost always inclusion-free: aquamarine and smoky quartz to name a couple. Then there are a bunch of stones in the middle- often having inclusions, like peridot, garnet and iolite. So, if you see an emerald that looks 'too perfect' with amazing bright color  but no visible inclusions, it's either got to be priced astronomically high, or it's not real (read: lab-created). Good to know!

The final category is cut. Cabochons (the bottom stones in the above pic) are usually worth less than faceted stones, simply because they don't take as long and require less skill to cut. Opals may be the exception to this rule. That said, there are many stones that are poorly cut- not symmetrical, with scratches, poor polish, and facet junctions not meeting up. This is a hard category to judge for the average person. It takes looking at a lot of stones to judge this one.

So, giving what you now know about stones now, take a stab at which of the above stones are worth the most??

answer: the pair at the left

Why? Well, the rectangular stone is the largest, that's true, but it's so full of inclusions that it's opaque. There's no transparency. It's a nice color, but not as rich and color-saturated as the pair on the left. They're also faceted, which adds to the value. And the cut is good- they're nice and deep, while the faceted stones to the right are quite flat in comparison, and the color is not as rich.

So, for these 7mm round faceted rubies, what's the cost? Well, they cost me $28 for the pair. Not as much as you thought, eh? Well, that's because there's a whole lot more quality available than this in a ruby. Sorry I don't have a really expensive one to show you :( Maybe someday.... The prettiest rubies I've ever seen are a lot more transparent and bright red than these.

If you want to see more stones and prices, simply do a search on Ebay and you can see a multitude of gem grades and prices. Of course, the best place to buy gems is from a reputable gem dealer. If something seems too good to be true, it probably is. Many gems today are artificially colored or treated. Or not even real. But that's a whole different post....

Sunday, August 5, 2012

Metal Clay Class with Wanaree Tanner

This weekend I was lucky enough to take a class given by Wanaree Tanner, who does AMAZING things with metal clay! Check out her website:

And here's her blog:

Wanaree is a full-time artist, super-nice, funny and down-to-earth lovely young woman. And best of all, it was located only minutes away from my home in Springfield, VA at La Ruche Davis Studio!  What's better than to spend the weekend chatting, creating, and eating snacks with a group of like-minded creative women artists? Here's the link if you ever want to take classes there (host Ann Davis is awesome!):

Wanaree has perfected the use of using a cutting machine, in this case the Silhouette Cameo, to cut metal clay bezels and more. In this class we learned how to do this by constructing a stone pendant with a bezel she custom cut for us made from COPPRClay.  Can't wait to try more of it on my own!  Here is the machine below:

 In addition, she uses a great technique utilizing Scratchfoam, which is a very thin styrofoam. We used a small ball burnisher to create designs in the foam, and pressed the wet clay into it, creating a texture to the back of our pendants.

Here is a picture of the Silhouette Cameo cutting my bezel:

She rolls out a sheet of COPPRclay to one more than the lowest setting on a pasta machine (she rolls it within a heavy plastic bag lined with Cool Slip or olive oil to prevent sticking). Then she lets it dry and runs it through the machine dry (but not too dry- keep it in a baggy when it's initially dried or it'll get too brittle). You can see below my piece of bezel removed from the Press n' Seal wrap that it was stuck on to prevent it moving on the cutting mat. I also cut out some circles with a piece of brass tubing to use on my bail:

I chose a thick lapis stone and we enlarged it on the copier because the COPPRclay shrinks when fired. We then used this copy to create a polymer clay 'stone' to use to measure and form the bezel at the enlarged size.

We used PasteMaker solution to create a paste with the clay in order to join and attach the bezel to the backplate. We also made the bail and connecting u-shaped pieces. Everything was dried in order to connect using PasteMaker. Moisture Mist may also be used on the bezel to increase flexibility around the stone.

Above is an example of one of Wanaree's stacked bezels, fired and stone set.

Here are my pieces before being joined. I created a dangle using the pieces cut out from the bezel wire, too.

Here are the 3 pieces all connected with u-shaped pieces of dried clay and paste. It needs to totally dry before firing. A dehydrator was used to speed up drying.

 And here are pics of the finished piece:
No major failures during firing. Some cracking appeared in which we used another copper clay product, with a faster firing time, to correct. Some distortion and uneven shrinking occured, but nothing too major. Some students in the class had more problems after firing than others- it seemed pretty random! Wanaree didn't think my dangle would work, but we were both happy to see it fired well and stayed put!

And here is a pic of the back of my piece (still needs some clean-up!!) with my Scratchfoam design:

 I still have some clean-up to do on the piece, but I think it turned out pretty well. Can't wait to try out my very own Silhouette Cameo for etching glass with vinyl stick-ons, fun with paper, rolling mill experiments, and maybe cutting keum-boo pieces too! Stay tuned!