di·a·mond 
(dīə-mənd, dīmənd)
(dīə-mənd, dīmənd)n.
1. An extremely hard, highly refractive crystalline form of carbon that is usually colorless and is used as a gemstone and in abrasives, cutting tools, and other applications.
2. A piece of jewelry containing such a gemstone.
3. A rhombus, particularly when oriented so that one diagonal extends from left to right and the other diagonal extends from top to bottom.
4. Games
a. A red, lozenge-shaped figure on certain playing cards.
b. A playing card with this figure.
c. diamonds (used with a sing. or pl. verb) The suit of cards represented by this figure.
5. Baseball
a. The infield.
b. The whole playing field.
adj.
Of or relating to a 60th or 75th anniversary.
tr.v. di·a·mond·ed, di·a·mond·ing, di·a·monds
Idiom: To adorn with diamonds.
diamond in the rough
One having exceptionally good qualities or the potential for greatness but lacking polish and refinement.
[Middle English diamaunt, from Old French diamant, from Medieval Latin diamās, diamant-, alteration of Latin adamās; see ADAMANT.]