As a precious gem, tanzanite stones are rarer than diamonds, but they don't have the same industrial strength that is associated with the more common precious gemstones, nor do they cost the same. Tanzanite comes from a roughly 20-square-mile region in the Merlani foothills in Tanzania at the base of Mt. Kilimanjaro. Each successive year, the gemstone is harder to find, since it is only found in this one location in the world. Tanzanite’s increasing rarity also contributes to its rising per-carat price.

Both tanzanite stones and diamonds are graded similarly: by cut, clarity, color, carats and overall stone quality. Even though tanzanite is more rare, diamonds cost considerably more per carat. At the time of publication, a 1-carat tanzanite ring costs roughly $1,000, but a diamond costs $2,475 or greater per carat. High-quality and well-known jewelers can charge even more for finished jewelry using either or both stones, based on their reputation and the quality of the gemstone setting.

Tanzanite gemstones range in colors from blue to purple, but the stones can display different colors when held in the light based on how they were cut. Diamonds also range in color, from yellow, pink or blue – like the Smithsonian’s Hope Diamond. The scale for gauging diamond colors begins with colorless stones, and then moves on to near colorless, pale or faint yellows all the way to noticeable color.

Poorly colored or flawed diamonds aren’t out of the mix. Instead, these diamonds are used for industrial purposes. You can find diamond-cutting blades for craft and home projects, and sometimes, diamonds are used as an abrasive. Tanzanite, which doesn’t have the strength of diamond, is a more brittle stone, with a 6 to 7 rating on the Mohs mineral hardness scale, compared with diamond’s position at 10, the top of the scale.

Both diamonds and tanzanite are too expensive to use in crafts unless you make handmade jewelry. Since 2012, the Tanzanite Foundation has funded the Maasi Ladies Project, which features handmade jewelry of the women who live near the region where tanzanite is mined. Since 2012, these women have made a distinctive wire-wrapped jewelry using tumbled tanzanite. Crafters often use replicas of tanzanite or diamonds in glass form instead of the real stone, or they use semi-precious stones.