Man-made Alternatives
Cubic zirconia, sometimes referred to as "zircon," first hit the jewelry market in 1976, and it has remained the most realistic and cost-effective alternative to a natural diamond. Though it is not a naturally occurring stone, the appeal of cubic zirconia lies in its ability to disperse light similarly to the way a diamond does. This gives the zircon the same sort of brilliance that is valued in diamonds.
There is understandable confusion about the difference between cultured diamonds and cubic zirconia. Though they are both man-made, cultured diamonds are said to have the exact same properties as a natural diamond. A rough diamond is created in a laboratory and is then cut and faceted exactly as a natural diamond would be. To the naked eye, cultured diamonds are identical to mined diamonds, but they are much less expensive.
Moissanite
Moissanite is a unique gemstone in that it is not formed on earth: it is found in meteorites that have fallen to earth. Jewelrymall.com reports that moissanite is a popular diamond alternative and that some people find moissanite to be more beautiful than diamond, because it reflects more light and is more brilliant. Despite its rarity and growing appeal, moisannite is also considerably less expensive than diamond.
Beryl
According to the website Bernardine.com, beryl is a valuable gemstone whose various colors are known by many other names. Colorless beryl is often referred to as goshenite. Goshenite is a hard gemstone, though not as hard as natural diamond. It rates a 7.5 to 8.0 on the Mohs scale. Besides its appearance, colorless beryl, or goshenite, may be a suitable alternative for diamonds in engagement or wedding rings because its lore includes a claim that it promotes marital love.
Topaz
Yellow topaz is known as a birthstone for November and blue topaz for December, but topaz also comes in a clear variety that looks strikingly similar to a diamond. In fact, a clear topaz substitutes so well for a diamond that the famous "Braganza Diamond," a stone in the Portuguese Crown jewels, was eventually identified as a clear topaz, even though it was believed for years to be a genuine diamond.
Sapphire
Perhaps most popular in their blue variety, sapphires come in many other colors, including white. A white sapphire is similar to a diamond not only in outward appearance, but in its hardness as well. Second only to the diamond, sapphire rates a 9.0 on the Mohs scale of hardness. A sapphire can be faceted and cut into the same shapes as a diamond. This may be one of the traits that made sapphire a popular diamond alternative in the early part of the twentieth century.