You're ready to go shopping? Print out this checklist and take it along with you to the jeweler's. As you satisfy all of the factors on this sheet, you will be determining the perfect tanzanite for you. So, grab a soft cloth to clean each stone, a 10X magnifying loupe, and hit the stores. And remember the main thing: Have fun!

Color: Tanzanite is a trichoic (three-colored) gemstone. Look for shades of purple, violet, red or orange in this mostly blue stone. Determine the hue (predominant color) tone (prominent secondary colors) and purity (consistency of color and lack of brown and gray.)
Examine the stone under many lighting sources, from all angles and then again under regular daylight to truly pinpoint the exact quality, tone and uniformity of color of each stone. Deep dark-blue is the most valuable hue for tanzanite but is hard to find in stones under 2 carats.
Pick a hue that suits your skin tone, wardrobe and hair color.

Clarity: Compare stones of similar shape, color and size. Tanzanite is typically "eye-clean" (free from visible flaws) look closely under various light sources and from every angle. Look for flaws that block transparency and uniformity of color. Keep an eye out for cracks, they can threaten durability. It's always discern flaws and clarity in loose stones.

Carats: Compare stones of like weight, cut and overall quality. Think in terms of "price-per-carat" not total cost. Watch out for "total weight" price tags, you want to know the cost-per-carat of the stone prior to setting. Stones under one-half carat will be priced in millimeter size, not carat weight. Tanzanite under 2 carats typically won't have the deep dark-blue of the most precious stones.

Cut and Style: Round and trilliant ("brilliant" cut with 58 facets in triangular shape) styles will cost more than other cuts and shapes. Think proportion and symmetry and examine the stone from all angles. Make sure there is not a large "window" when viewing the stone from the top. Is the culet (bottom point) centered? From the profile is the depth good? (keep familiar diamond symbols in mind.)