1. An extremely hard gemstone used mainly for jewelry, tools and as an investment in precious stones.

2. The informal term for an index-based unit investment trust, known formally as Diamonds Trust Series 1.

2. The Diamonds Trust Series 1 trades on the American Stock Exchange under the ticker symbol "DIA". It is commonly referred to as an exchange-traded fund (ETF) by the investing public and the financial media; however, this is not entirely accurate. A share of DIA provides an investor with a fractional ownership in the 30 stocks represented in the Dow Jones Industrial Average (DJIA) index.