emmy's posterous

Many years ago I took an afternoon class, "The Scottish Gemologist". I HAD to, being a MacKenzie. The main point of the class was that it is possible to tell quite a lot about a stone with just your eyeballs, and some magnification. I enjoyed that class. Recently I had the opportunity to put it into practice. A friend gave me a handful of golden colored faceted stones. She knew some were citrines and thought that some were glass. Last Friday I felt like it would be fun to sit down and see if I could separate the glass from the Citrine. Citrine, like Amethyst, is quartz, one of the most common minerals on earth. Photo showing rounded facet junctions on stone on left, and color banding in stone on right.

I was wearing a head loupe and also used a 10 power hand held jewelers loupe. ( I just did a test; wearing my reading glasses and using the little super magnifying circle in a common magnifying glass, I was able to see almost as well.) I began with the largest stones. The first thing that I noticed was that the facets on the bottom part of the stone, the pavillion, had a smeared appearance, or very slight parallel scratches. A properly cut and polished gemstone has perfectly smooth facets. 

 

Photo showing depression where cast material has contracted upon cooling. Also streaky lines on facet planes.

Having been clued in that some of the stones were probably glass, I was looking for two characteristics which are strong indicators for glass. The first, tiny gas bubbles inside the stone. The second is conchoidal breakage. Conchoidal breakage is where damage to the stone has the appearance of a shell, a scallop shape with concentric ridges. This damage often occurs where the stone has been set, such as under a prong. Conchoidal breakage is very typical on glass but can also be found on quartz. For the stones I was looking at, the occurrence of conchoidal breakage was not going to help me definitively distinguish between citrine and glass, but it is easy to spot, and interesting. I found both conchoidal breakage and gas bubbles in a couple of the stones.

By this time I was pretty sure that the large square stones were glass. But I was into it now. I noticed that the facet junctions, the ridge where two facets meet, were not super crisp, but very slightly rounded. An indication of glass that has been cast in a mold. The facet junctions on cut gemstones are very crisp.

Suddenly I saw something which I should have seen immediately, because I could see it with my naked eyes, and that was that the material had contracted upon cooling! Each of the 3 large stones had this, and on one, the one in the photograph, it is very apparent. So definitely the 3 largest stones were cast in molds, they could even be hard plastic, which might account for the streaks along the facets. The more I looked, the more I noticed. The last thing that I saw was that in the smaller rectangular stones, there is color banding, something found in gemstones, but not glass. Finally, and this is subtle, the 5 smaller stones felt cooler than the 5 larger ones.

Photo showing the impostors on the left and the genuine citrines on the right.

My conclusion, the 5 largest stones are glass, or maybe plastic, and the 5 smaller stones are citrine. A fun and interesting way to spend 45 minutes. I came in and told my husband what I had been doing, and he said "blog post", so here it is! Happy Scottish gem sleuthing!

 

Today my main task in the shop was to finish a skull ring with Mexican fire opal eyes. Here is a picture of the ring, and the stones. I have already annealed and pre-polished it.

The first step is to measure the stones, exactly, and select a rotary bur of corresponding size. The best way to describe this setting would be to call it a modified channel setting. One side of the setting will be under cut, and the other side will be hammered over the stone.

First I cut a small notch in the lower area of the eye socket of the ring. That will hold the bottom edge of the stone. While cutting that notch, I slightly tip the bur up, to cut a seat for the upper edge of the stone. The stone should slip into the lower notch and rest against the upper seat.

Once both stones are properly seated, level, even and deep enough so that there is sufficient metal to secure them... I hammer the metal over the upper edge of each stone. This is sort of a brutal setting process. I would never try setting delicate stones (emeralds, tanzanites, even some opals) in this way. I use a steel punch to move the metal over the upper edge of the stone, wedging it into the lower notch. This is a very secure setting. Plus, the stones are recessed, and therefore protected from wear. Sometimes people ask me if the stones are glued in. I hate glue! Glue will always fail over time. Once the stones are tight, I have to remove the tool marks. I do this with a rubber wheel in my flexible shaft drill. Carefully! The coarser of the rubber wheels will damage the stones if they are accidentally touched!

Next, to color the recessed areas black, I immerse it in a warm, stinky bath of liver of sulphur. Think rotten eggs. The above picture shows the ring just after the liver of sulphur.

Finally, the polisher:

Final polish is a 2 step process. The first go over is with a gentle abrasive compound, tripoli, that removes the black from the high points. Then I wash the ring, removing all traces of the tripoli. Finally, I obtain a high luster with red rouge polishing compound on a cotton wheel.

Done! Ready to ship :-)

 

 

I have a well-equipped shop set up for all aspects of making cast and
fabricated jewelry. Some of my tools include a kiln, a casting
machine, a vacuum machine, a polisher, a sand-blaster, an ultrasonic
... (wow, the list goes on and on).... And I have a whole variety of
specialized hand tools for stone setting and fine finishing work.

I am a jeweler and goldsmith working out of my home studio in Boulder
Creek, California. Boulder Creek is located in the beautiful Santa
Cruz mountains where the redwoods meet the ocean.

I do all the jewelry work myself. Everything I make is handmade by me!
I carve my own wax. I do my own casting. I do my own stone-setting and
finishing. I take pride in making unique high-quality jewelry using
traditional old-world goldsmithing techniques.

I've been selling my jewelry on the internet since 2001. Now, it's
finally time for me to start a blog! I'll be discussing my work,
showing some pictures, maybe adding a tutorial showing some
jewelry-making techniques...