2. GARNET Garnets are a group of closely-related mineral gemstones that come in a wide variety of colors.

3. These trillions are stunning examples of fine color amethyst from the Four Peaks mine in Arizona. AMETHYST

4. This rough crystal (left) shows the classic seawater color aquamarine is named for. The fashioned stone (right) was heat treated to achieve its fine color. AQUAMARINE

5. Bloodstone is a type of jasper with a distinctive look: red to brownish red flecks scattered across a dark green background BLOODSTONE

6. DIAMOND

7. This untreated 10.86-ct. Colombian crystal shows the slightly bluish green color of the finest emeralds. EMERALD

8. PEARL AND CULTURED PEARL Akoya cultured pearls

9. PEARL AND CULTURED PEARL

10. ALEXANDRITE Alexandrites display a stunning color change under different lighting, going from green in daylight and fluorescent light (left) to red or raspberry in incandescent light (right). This color combination prompted the romantic description, “emerald by day, ruby by night.”

11. MOONSTONE Moonstone shows the phenomenon adularescence. The finest material is near-colorless with a blue sheen that moves across the stone.

12. RUBY Ruby can command the highest per-carat price of all colored stones.

13. PERIDOT The finest peridot is a richly saturated green to slightly yellowish green with no brownish tints. The depth of color in this 172.53-ct. faceted gem is especially rare for peridot.

14. In sardonyx, white or black bands alternate with reddish brown bands. SARDONYX

15. SAPPHIRE Sri Lankan or Ceylon Burmese Kashmir

16. FANCY SAPPHIRE Sapphires in any color other than blue are called fancy sapphires.

17. Opal displays the play-of-color phenomenon. OPAL

18. TOURMALINE Tourmaline occurs in the widest variety of colors of any gem.

19. Most topaz crystals start out colorless and turn blue after treatment with a combination of irradiation and heat. TOPAZ

20. CITRINE Citrine is the yellow to reddish orange variety of quartz.

21. TURQUOISE Color is turquoise’s prime virtue. It can be greenish blue, bluish green, or even yellowish green, depending on its iron content. But the most highly-valued turquoise is an intense, evenly distributed, medium blue, known in the trade as Persian blue.

22. ZIRCON Blue is the most popular zircon color, but the gem comes in a variety of hues including brown, red, green, and yellow.

23. TANZANITE Tanzanite is an attractive blue to violetish blue to bluish purple gem from Tanzania, Africa. Some jewelry organizations have added tanzanite as an alternative December birthstone.

24. Credits Columbia Gem House, Inc. De Beers (Diamond Promotion Service/Diamond Information Center) Tino Hammid ICA (International Colored Gemstone Association) Alan Jobbins Marisa Goebel LaBelle John Parrish Jeffrey Scovil Timeless Gem Designs Harold & Erica Van Pelt Robert Weldon