Another possibility for imitating sapphire (blue corundum) is blue quartz, which gets its coloration from inclusions of crocidolite or rutile fibers. Yet another possibilty is dumortierite quartz, also known as blue aventurine. The latter tends to be semi-opaque, while blue quartz is more translucent (compare with green aventurine). I haven't seen enough of either on the market to judge their respective qualities. Based on what little I have seen, I tend to favor the blue quartz over the blue aventurine. I have seen some rather nice specimens of blue quartz, from Madagascar, being sold on the internet. Both matierials have a Mohs hardness of '7', making them durable enough for any jewelry application. Blue aventurine tends to resemble denim lapis rather than corundum. Both types of quartz are less expensive than blue topaz (roughly half the cost). The trick is finding a reliable supply.
fake is period
This is a cool article. I was under the impression that fake gemstones were period no? I heard once they were made out of glass or glass paste. I have seen similar things in museums. Sabine 06:59, 21 November 2006 (EST)
Indeed some of the info about particular imiattions says which were period substitutions. It would be great to have more detail though. I've edited the introduction to enhance the mention that imitation gemstones is a period practise. If anyone fancies oing a google search, links ot period examples of carbacons and other imitations would be much appreciated.Tiff