While chatting with the wonderful Barbara Mann last week, I learned a bit about organic gems. Barbara is a well known metal and jewelry artists in Athens, GA and we were discussing organic gems. I always say that pearls are one of the only organic gems comparable only to ivory which is actually considered a mineral, not a gem. And then Barbara pointed out coral. Hmmm..
So, what is the deal with coral? It is, in fact, considered an organic gem (I had to go back and do some research!). Now, by organic, we mean they are formed by an organism or as part of a biological process. Coral is a spineless marine animal. They are a few millimeters in diameter, are comprised of a jelly like substance; they have a mouth and tentacles. But, they are not solitary organisms. They live in colonies of genetically identical polyps. They secrete an exoskeleton which is what we know as coral. The exoskeleton is the part that contributes to coral reefs and, of course, jewelry.
The most interesting thing to me is that coral is surprisingly similar to pearls. They are both primarily comprised of calcium carbonate (that is the main pearl making and coral making material), they are created by invertebrates, they originate in the water and they are truly soft and sensitive gems. Very cool.
So, out of interest of being thorough, what are other organic gems? Amber is an organic gem produced by trees. So, you have tree sap which is a fluid which helps cells transport water and nutrients through the tree and then you have resin which is the hydrocarbon secretion (basically, think of it as the organic breakdown) from a tree. Amber is fossilized tree resin from very old trees. It has the rich yellow coloring which has been admired and appreciated for many years and is used in medicine, jewelry and other ornaments.
Exploring amber introduces me to the term mineraloid, which is a mineral substance which does not crystalize. Crystals are defined by their microscopic atomic arrangement. If a substance does not have a certain crystalized pattern, they are considered a mineraloid. Now, pearls have crystals. In fact, they consist of a layering of interlocking crystal layers but the cement that glues those crystal layers together is an organic material, conchiolin. This causes pearls to be classified as a mineraloid versus a mineral.
Let's explore more organic gems. I have long seen jewelry mixing pearls and jet and I truthfully thought jet was just a black bead. They go well with pearls because they are strung the same way, with knots between each beads. Some jewelry even alternates jet beads with pearls. They were great jewelry for those women in the 19th century who had to mourn for long periods of time. It was also very fashionable in the 1920s and 1930s. Jet is another organic gem. Jet is mistakingly referred to as black coal although it does give off a coal odor if you touch it with a hot needle. So.. what is jet, exactly? It is decomposing wood which forms under high pressure. So, a carbon substance decomposed under high pressure... it even sounds like coal. But, coal is actually older than jet and coal is the result of a mass vegetation decomposition whereas jet originates from trees, usually specific varieties. Petrified wood actually popped in my head but it is different too, being a form of fossilized wood.
Finally, we should talk about ivory. We all know about it. It is extremely controversial since so many elephants have been slaughtered for their ivory tusks. Ivory does not come strictly from elephants, though, pigs, hippopotamus and walrus create ivory too. Ivory comes from tusks and teeth and it is made of a tissue similar to bone. It is used in jewelry but it also has many practical and ornamental uses too.
And that is the scope of organic gems. If you can think of any more... please let me know!