As the old song goes, diamonds are a girl's best friend. But what imparts to diamonds the value that compels a young man to express his undying love by offering the gem to his intended bride? Is it the permanence of diamond, one of the hardest, least compressible and stiffest materials known to man, able to withstand extreme tempuratures, impervious to most acids and alkalis? Perhaps it is the diamond's radiant luster, conferred by the highest reflectance and index of refraction of all transparent substances.
While such properties (and no small amount of marketing from the jewelry industry) have made diamonds the world's most popular gemstone, they also make diamonds invaluable in many industrial applications. Many industrial diamonds are cultured, or lab-grown, by such methods as detonation, high-pressure-high-tempurature, ultrasonic cavitation and chemical vapor deposition. Due to their hardness (ten on the Mohs scale), they are used commercially as super abrasives for grinding and polishing, and are imbedded in coatings on tools such as drill tips and sawblades.
Diamonds are also exceptional thermal conductors, are electrically resistant, have an extremely low thermal expansion, are transparent from the far infrared through the deep ultraviolet, and are one of only a few materials with a negative work function (electron affinity). Their increased availability due to lab production vastly extends their potential use of both the fluorescent and non-fluorescent forms.