The name “diamond� derives from the ancient Greek adamas (“invincible�). They have been treasured as gemstones since their use as religious icons in India at least 2,500 years ago— and usage in drill bits and engraving tools also dates to early human history. Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.