I find that more and more I'm loving the CS discussions pertaining to stone inclusions and telltale signs of treatment. Could anyone (Chrono? Rockhugger? VL?, TL?, LD?, Pandora?) recommend a good book or two with good photographic examples of inclusions?
All my books are GIA. You could do a search on eBay for a GIA gemstone identification book. I am sure there are consumer books available too. I have never read them though so I can't recommend anything.
VL: I am truly honored that you are truly honored...
I have treenbean's site bookmarked and refer to it often - thanks for the suggestion.
Right now, my question is prompted by a little spinel I got. When I loupe it, it looks like it has little pinpoints of something in the stone - not at all to the point of distracting from its sparkle, but I was curious what they were. For lack of a better descriptor, I might have called them bubbles (they're so small that I can't actually tell if they are hollow or solid), but then there was a discussion about another stone (can't even remember which) where CS experts were saying that bubbles were a sign of synthetic. So despite the fact that these pinpoints in my stone might be true inclusions, the paranoid part of me would like to verify that these are a standard type of inclusion for a spinel.
I would provide photos, but my ornery and uncooperative teenager took his camera back and won't let me use it (it's being held as leverage for something he wants, no doubt).
Pinpoints are usually little tiny crystals inside of the stone. It is very normal in spinels, and a good sign it's natural. Bubbles usually mean glass imitation. But a simple Specific gravity test can fix that. If you would like I can show you how to do it at home.
I invented this 'at home SG kit' back in the day to tell apatite and tourmaline apart.
You need a scale that measures .01ct
Thin wire
Gem jar with room temp water in it
And a gem
Weigh the gem on the scale, write that number down.
Bend the wire at one end so it makes a loop to hold the gem in.
Put the jar with water in it on the scale. Turn it on and let it calibrate to 0 with the water on it.
Put the gem on the wire and slowly lower it into the water will it's completely submerged. Do not let the wire or gem touch the bottom of the jar. Write down the measurement.
The dry weight divided by the submerged weight equals the specific gravity. I allow .05 differential for the wire.
There's a good book that assumes a bit of knowledge and is for those who want to go one step further without being too technical called "Identification of Gemstones" by Michael O'Donoghue and Louise Joyner, published by Butterworth Heinemann. I'm sure it's available on Amazon and is less than $40.
It has chapters on gem testing, diamonds, corundum, beryls, opals, quartz, jade, chrysoberyls, topaz, tourmaline, garnets, spinels and the list is endless. It also has some fascinating photos. The bits I love are in each chapter they will tell you a story about a particular gem that was submitted for testing and what was unusual, what they found and how they identified what they found!
It's fairly easy reading and not too hard going! It would be good to have more photos but those it has are very interesting.