Precious Gemstones: What's Valuable, the Truth About "Investment Grade" Stones, and More

With hundreds of different types of gemstones and a whole spectrum of colors, trying to understand the value of your stones can seem overwhelming. Nearly everyday, someone asks us to identify their gemstones and what they might be worth. One of the most common situations we encounter is a client who purchased stones that were sold to them as an investment. 

The most frequent gemstone we see that has been sold as an investment is, by far, tanzanite. Tanzanite is a vivid purple-blue variety of zoisite that was discovered in Tanzania in the late 1960s. Marketed heavily by Tiffany & Co., it quickly became very popular. Its popularity surged again when the American Gem Trade Association made tanzanite December's new birthstone. Thus, many buyers thought that it would become worth much more than they paid someday. Unfortunately, tanzanite sells for about $50-$350/per carat wholesale. The two biggest reasons for this are its lack of durability and the fact that it must be heat treated to achieve its color. As a general rule, natural, untreated stones with a Mohs hardness above 7 are much more valuable such as sapphires and emeralds. 

So, what gemstones do hold their value well? Here is our list of the most desirable gemstones:

1. Corundum: Sapphires & Rubies 

Art Deco Yogo Gulch Sapphire Brooch

Natural, untreated blue sapphires, padparadscha sapphires, and rubies of fine quality are incredibly valuable. Origin is one of the biggest factors when determining value, but we will get into that at another time. In 2015, a natural Burmese ruby necklace set a world record at Christie's when it sold for $1.2 million per carat. 

 2. Emeralds

Loose Natural Emerald

The most valuable material is untreated and hails from Colombia. In 2017, Christie's sold a Raymond Yard emerald ring for $305,000 per carat. 

3. Opals

Though you might be most familiar with white opal, black opal is the most desirable variety. The most valuable opals come from Lightning Ridge, Australia. 

4. Alexandrite 

Extremely rare and often very small, alexandrite is a variety of chrysoberyl highly prized for its ability to change colorsFrequently what is sold as alexandrite is actually synthetic color-change spinel. In 2014, Christie's sold a loose alexandrite for $62,000 per carat. 

5. Jade

The best jade is translucent, vivid green. However, jade comes in a variety of colors such as lavender, red, black, white, and more. In 2014, Sotheby's sold a strand of jade beads by Cartier for a little over $27 million dollars. 

6. Pearls

Cartier Natural Pearl Stick Pin

Pearls are an interesting market because cultured pearls are worth very little, but natural pearls can be worth astronomical prices. In 2016, Christie's sold a pendant with a single pearl for $1.5 million dollars. 

7. Paraiba Tourmaline

Brazilian Paraiba Tourmaline

Tourmaline comes in nearly every color, but its Paraiba variety is the most valuable by far. Ideal Paraiba stones are an exceptional neon Caribbean blue. In 2017, Christie's sold a Tiffany Paraiba ring for $73,000 per carat. 

Popular gemstones like Tanzanite that do not have significant second-hand value include blue topaz, amethyst, peridot, zircon, and red garnet. 

Should you ever buy a gemstone marketed as an investment? We would never sell a gemstone to a client with the pretense that it is going to appreciate in value. Are some gemstones a better investment than others? Yes, but the colored stone market is incredibly complex and volatile just like any other market. The best thing you can do is buy something you think is beautiful from a knowledgeable gemologist who specializes in gemstones.