Blue Sapphire Guide

Buying tips, facts & history



our source

Our Source

mineral class

Mineral class


9 Mohs Scale

birthstone month

Birthstone month

wedding anniversaries

Wedding anniversaries
5th and 45th

blue sapphire facts

Hard Facts

Sapphire is a precious gemstone, formed from a mineral called corundum. Blue sapphires get their colour from titanium and iron trace elements. On the Mohs scale of mineral hardness, blue sapphire rates 9 out of 10, so it is a very durable gem. The word ‘sapphire’ comes from the Greek word sapphirus which means blue.

where on earth?

Where on Earth?

We source our sapphires almost exclusively in Thailand. Sapphires are mined in about twenty different countries including China, Madagascar and Australia. But Thai sapphires are very sought after because of their high quality, and the country’s modern, ethical mining practices.

september birthstone

Birthstone and Anniversary

Sapphire is September’s birthstone. It is also traditionally gifted on 5th and 45th wedding anniversaries. Blue sapphire is said to bring luck, loyalty, happiness and love. Its symbolism and durability make it ideal for engagement rings.

blue sapphire buying guide

Buying Guide

How should you assess a blue sapphire’s quality and value? Our gem experts determine a blue sapphire’s worth in a way that is very much the same as grading diamonds. Clarity is the foremost consideration, followed by colour, cut and carat weight.


The primary hue of blue sapphires is, simply, blue. However, blue sapphires are natural gemstones, so their colour can vary from light to dark. To identify the best gems, our experts look for vivid colour combined with good clarity, rather than a specific tone.


Blue sapphires that have a combination of good clarity and colour are rare. Large sapphires are therefore much more expensive per carat than small sapphires of the same quality. For example, the blue sapphire on the Duchess of Cambridge’s engagement ring weighs 12 carats. But the typical sapphire jewellery sold on the high street only goes up to about 5 carats.


Commercially sold sapphires typically have some natural inclusions. Completely clear sapphires are extremely rare, and therefore very expensive. We place emphasis on sapphire clarity. Our gemmologist looks for sapphires that have minimal imperfections and allow light to pass through them, creating lots of sparkle.


A good cut will not only bring out a sapphire’s sparkle, but also flatter its natural colour. What’s more, it will minimise or hide any natural inclusions. The most popular cuts for a sapphire are oval and round. These are used in all types of jewellery to bring out the sapphire’s best sparkle, colour and clarity.

natural or treated blue sapphires

Natural or Treated?

Our gem expert would always recommend buying natural sapphires, rather than coloured or heat-treated ones. That’s why all the sapphires we sell are natural.

Small inclusions or markings are a sign that your sapphire is genuine and untreated. These natural markings remind us that each gem formed under the Earth’s surface more than 2 billion years ago, and no two are alike.

blue sapphire care

Care and Cleaning

Sapphires are very durable gems. However, they are natural precious stones, and should be treated with care. This means that you shouldn’t scrub them harshly or exert excessive pressure on them when cleaning.

The safest and cheapest way to clean your sapphire jewellery is with warm water and mild soap, scrubbing gently with an old toothbrush. Use a bowl rather than a sink, so there’s no risk of your gems falling down the drain. Afterwards, pat your jewellery dry with a lint-free cloth or leave to air dry.

modern history

Modern History

Today, blue sapphires are considered to represent loyalty, truth and honesty. They are also closely associated with royalty: blue sapphires feature in several countries’ crown jewel collections, in particular Holland and the United Kingdom.

The most famous blue sapphire of our time is the one on the Duchess of Cambridge’s engagement ring. Find out more about this beautiful piece of jewellery below, under Famous Sapphires.

famous blue sapphires

Famous Blue Sapphires

Right now the most famous blue sapphire in the world is the one Prince William gave to Catherine Middleton for their royal engagement in 2010. The ring originally belonged to his mother, Princess Diana. It is now considered a royal heirloom, valued at more than £300,000. The ring’s blue sapphire weighs a staggering 12 carats and is cut into an oval shape. It is set in 18K white gold and surrounded by diamonds.

legend and myth

Legend & Lore

In old Persian lore, the Earth was said to be balanced on top of an enormous sapphire and its reflection gave the sky its blue colour.

The ancient Greeks and Romans also claimed blue sapphires held mystical powers, giving their owners wisdom and health. In the Middle Ages, blue sapphires were often worn by royalty as amulets to ward off evil.