In some countries, in particular Japan, all gemstones are sold with a laboratory certificate. A certificate or identification report confirms the gemstone variety and natural origin of the stones. In some countries, a certificate may also include information about where the gemstone was mined, based on a study of its inclusions. But although certificates from a major laboratory provide support for your purchase, in many countries, including the United States, there is no official regulation of who can offer a certificate.
Some certificates are reliable and some are just fancy letterhead and some guy's signature.
Even certificates from reputable labs can be forged. Certificates are a common feature to gemstone investment scams, especially common in sales pitches over the telephone or, increasingly, on the Internet, so be careful about accepting them as some kind of guarantee. Never buy a gemstone in a sealed package and never buy a gemstone by certification alone, over the telephone, as an investment. Gemstones are not a liquid investment and you should be very wary of anyone who sells them as if they were a security. Offers to repurchase the portfolio whenever you want to sell won't do you much good if the firm has disappeared.