Of Beryllium and Beefsteak

Posted on November 12, 2010 by John L. Emmett, PhD

Diffusion in gemology can be defined as a method of artificially coloring gemstones, not unlike the dyeing of cloth.

Diffusion is actually a very common process that we meet in many different contexts. The dying of natural textile fibers is a diffusion process, which is why the longer the fabric is in the dye pot, the darker the color achieved. The color deepens because the dye diffuses deeper into the fiber and makes a thicker and thus darker color layer.

While diffusion processes can be useful in producing low cost gems from very low value rough if it is clearly disclosed at all levels in the marketplace, it is a fact that all the diffusion processes in gemology that are used to color gemstones have been brought to the marketplace without disclosure. One would be naïve not to assume that in all cases the objective was to defraud the buyer.

Chemistry in a Solid
Most people are familiar with chemical reactions in a liquid— for example the reaction between vinegar and baking soda. The two chemicals in this case are brought in contact with each other by mixing—putting a spoon into the mixture and stirring. Two chemicals in a solid can react with each other also. But we can’t stick the spoon in to stir them.

So how do two chemicals in a solid get together? They find each other by a process called diffusion.
Chemical reactions take place in solids much as they do in liquids. The difference is simply that we can stir liquids
to mix the chemicals, but in a solid it is the diffusion…

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