Web Metrics and Site Analytics by WebSTAT

There have been some exciting finds in the gem world through the centuries. Incredible precious stones that come to mind include the Great Star of Africa or Cullinan Diamond, and The Star of India.

One famous jewel that became the most expensive gemstone sold at auction is the CTF Pink Star. Formerly known as the Steinmetz Pink, this flawless pink diamond sold for USD 71.2 million at Sotheby’s in Hong Kong in 2017.

However, it isn’t only diamonds that are rare and expensive. Several different varieties of gemstones are incredibly rare but still used in jewellery on occasion.

Aren’t all gemstones rare?

All gemstones are rare to some degree, but a select number are much rarer than others. The term, gemstone, covers a number of elements including minerals, organic matter, and rocks, that have certain qualities such as aesthetics or rarity.

These gemstones are then cut and polished to produce the jewels that you see in jewellers online and in retail outlets.

The rarity of gemstones is part of what drives the price of jewels. But gemstones can be precious or semi-precious. When it comes to the rarest gemstones though the price is the limit.

What are the rarest gemstones that can be found in jewellers today?

There are many seriously rare gemstones, and too many to do justice to in this brief article. But these are some of the rarest.


This stone was named after Alexander II after vast reserves were discovered in the Ural Mountains in Russia in 1830.


The appealing aspect of alexandrite is how it changes colour during the day and night depending on the light. Natural alexandrite rings will have a peacock blue colour during daylight and take on a purple-red color when light is reduced.

Alexandrite would make a striking alternative to a diamond if used for a wedding or engagement ring. If your budget allows.

Cost per carat

Alexandrite sells for up to USD 15,000 per carat or AUD 22,250.

Black opal

Of all opals, the black variety is the rarest. Black opals are only found in a few areas on the planet.


Trace elements of carbon and iron oxide give the gemstone its dark appearance. The dark colouring allows the other colours of the opal to pop.

Cost per carat

Black opal sells for up to USD 10,000 per carat or AUD 15,000.


No gemstone list could exclude diamonds. And although diamonds are not the rarest gemstone, due to their demand they are getting rarer. The most famous gemstones in history have invariably been diamonds with the Koh-i-Noor being perhaps the most famous and infamous.


Uncut diamonds appear like transparent rocks with a yellow tint, but once cut they will have a clear white brilliance that reflects rainbow colours. The value of this gemstone depends on the colour, clarity, cut, and carats. But, the Koh-i-Noor diamond is priceless.

Cost per carat

Diamonds sell for up to USD 16,500 per carat or AUD 24,800.


Richard Taaffe discovered the first example of this gemstone not in the ground, but in a jeweller’s shop in Ireland. It is the only gemstone to be named after it had already been cut and faceted. And taaffeite is one of the rarest minerals in the world.


Sometimes colourless, taaffeite usually appears pink, lilac, light mauve, red, blue, and occasionally green. The price of taaffeite is determined by the 4c’s as diamonds are.

Cost per carat

Taaffeite sells for up to USD 2,500 per carat or AUD 3,750.

Natural Pearl

Only about 1 in 10,000 wild oysters will elicit a natural pearl. Even when natural pearls are found, most of them will be unusable by jewellers.

When high-quality natural pearls are found, they can sell for exceptional amounts. In 2014, 53 natural pearls in a strand sold for US 2.9 million. However, that pales into insignificance compared to Queen Marie Antoinette’s pearl pendant which sold at Sotheby’s for USD 32 million.


The rarest pearls are gold in colour, but more common examples are usually cream with champagne and yellow undertones. You might be surprised to know that pearls can be black or pink as well. Prices for pearls vary dramatically so it is hard to give an exact valuation.

Cost per carat

Natural pearl sells for up to USD 3,000 per carat or AUD 4,500.


This gemstone was named after the Nobel Prize-winning chemist, Dr. Henri Moissan. Interestingly, this mineral was first discovered at a huge meteorite strike in Arizona in 1893. The jewellers at moissaniterings.us report this gemstone being very popular for engagement rings as an alternative to diamonds.


Moissanite appears very much like a diamond and is nearly colourless. This gemstone is very rare as very few of them are suitable for jewellery.

Cost per carat

Moissanite sells for up to USD 5,000 per carat or AUD 7,500.

Kashmir sapphire

This is the king of sapphires and is far rarer than even a D flawless diamond. After moissanite, sapphires are the second most popular alternative to diamonds for wedding rings.

The importance of a wedding ring is to demonstrate the commitment between two people, and if you really want to flaunt that, a Kashmir sapphire will do.


Kashmir sapphires are described as fuzzy, sleepy, and soft. A better description might be to compare them to the look of blue velvet. The price of Kashmir blue sapphires is said to have no upper limit for the highest quality stones.

Cost per carat

Kashmir sapphires sell for up to USD 60,000 per carat or AUD 90,000.


Tanzanite is found in only one country. This gemstone is named after Tanzania where it was found in 1967 by Maasai herders.

If you want to tanzanite jewellery, you should move fast. There will likely be no tanzanite left in the next 2 decades.


Tanzanite is blue with tones of violet and can be very intense and vivid. Surprisingly, despite being far rarer than diamonds, tanzanite is far more affordable.

Cost per carat

Tanzanite sells for up to USD 800 per carat or AUD 1,200.

Burmese ruby

Four gems are known as the most precious gemstones; diamonds, emeralds, sapphires, and rubies. However, one type of ruby is perhaps the rarest and most precious gemstone of all.

Burmese rubies come from Myanmar as it is now known, and they are far superior to any similar gemstones from other countries. The Burmese ruby is simply far rarer and more valuable than other rubies.


These rubies are brilliant red and bright. The colours range from pink-red to what is known as pigeon blood red. The price estimate below is just a guide, and Burmese rubies have sold for USD 1 million per carat before.

Cost per carat

Alexandrite sells for up to USD 60,000 per carat or AUD 90,000.


There are several more rare gemstones such as blue garnet, and benitoite. However, the gemstones listed here represent some of the most magical stones that can be used in jewellery today.

Some, such as Kashmir sapphires might be out of most people’s budgets, but others like moissanite are practical alternatives to diamonds, and more affordable. One thing is for sure, all the gemstones here would make striking centrepieces for jewellery.

Scroll to Top