Grey Amethyst

The four most sought-after precious gemstones are diamonds, sapphires, emeralds, and rubies.

Precious stones are distinguished by their quality, their rarity and the beauty of their colours. There are only four precious stones: diamond, sapphire, ruby and emerald. All other stones are therefore called semi-precious stones.

Yes, Opal is an extremely precious gem. Gem Black, Boulder, Crystal and White Opals are the world's #1 most valuable commercially available gemstone, yet they are complex with an exponentially large range of valuation characteristics than Diamonds, Rubies, Emeralds, Sapphires or Tanzanites.

The five traditional cardinal gems are:

1. Amethyst (purple) Rare and precious in the Old World until large deposits were found in Brazil.
2. Diamond (transparent)
3. Emerald (green)
4. Ruby (red)
5. Sapphire (blue)

Gemstones are composed of a variety of minerals, rocks, and organic material. With over 300 gemstones currently documented, there are bound to be some that are significantly more rare and valuable than the iconic diamond.

Thanks partially to Chinese demand, rare imperial green jade, a translucent stone that's been compared to fine emerald, is the most expensive gem in the world, worth more per gram than diamonds.

Opal is found around the world (Brazil, Mexico, Honduras and the western US) however Australia produces 95% of the world's precious opal and it is our official national gemstone.