Everything you need to know about Sapphires

The sapphire is one of the most recognisable gemstones due to its colour and hardness. From artisanal jewellery workshops to major luxury houses, the sapphire remains a common choice in jewellery such as rings or earrings, and also in watches for its elegant presence.

This gem from the corundum family has captivated humanity for centuries, adorning everything from royal crowns to modern engagement rings.

What is a sapphire?

The sapphire is a precious stone that belongs to the corundum family, a mineral composed of aluminium oxide (Al₂O₃). It is a gemstone of great hardness, with a value of 9 on the Mohs scale, making it perfect for use in fine jewellery.

Although blue is the colour most associated with sapphire, this precious stone can appear in a wide variety of hues. The colour variations are due to small amounts of other elements such as iron and titanium, which modify the tone of the mineral. There are pink, yellow, green, orange, white, and black sapphires, all belonging to the same mineral family.

The term sapphire comes from the Latin “sapphirus”, derived from the Greek “sáppheiros” and the Hebrew “sappir”, meaning “clean” or “brilliant”. It shares its origin with the ruby, as both are varieties of corundum: when the mineral takes on a red colour, it is classified as ruby; in all other tones, it is known as sapphire.

Physical properties of sapphires

Among the physical properties of sapphire, its hardness stands out — reaching the value 9 on the Mohs scale, surpassed only by diamond. This feature gives it great resistance to scratches and wear, which is why it is frequently used in rings, watches, and other exclusive pieces.

Regarding its optical behaviour, it has a refractive index ranging between 1.759 and 1.779, creating a clean and sharp brilliance that enhances the purity of its colour. High-quality sapphires show great transparency and light dispersion that intensifies their colour without the need for additional treatments.

Where in the world are sapphires mined?

The main sapphire deposits are distributed across various regions of the world, each with its own characteristics influencing the colour and purity of the gem. Kashmir, in northern India, is known for having produced some of the most highly prized specimens, recognisable by their velvety blue tone and rarity, as the mines have been largely inactive for decades. In Myanmar, sapphires of deep blue, with high saturation and clarity, are found, while Sri Lanka — historically called Ceylon — is famous for lighter-toned specimens, often with a violet hue. Madagascar has become one of the most important producers today, both in volume and quality.

There are also significant deposits in Thailand and Australia, where darker sapphires predominate, as well as in regions such as Tanzania, Kenya, Brazil, and Malawi, which add colour diversity to these precious stones.

The diversity of sapphire colours

The colour of a sapphire is one of the most influential aspects of its rarity and value. Blue remains the most recognised and appreciated variety, with tones ranging from light blue to intense blue. Among all, the cornflower-blue sapphire from Kashmir is the most sought-after for its velvety appearance, caused by tiny rutile inclusions that evenly scatter light.

Among the rarest varieties is the padparadscha sapphire, a unique gem with pinkish and orange hues that form a very uncommon balance in nature. Its name derives from the Sanskrit term “padmaraga”, referring to the colour of the lotus flower. The specimens extracted in Sri Lanka are especially valued for the purity and brightness of their tones.

In addition to these varieties, there are the so-called fancy sapphires, a term that encompasses all non-blue versions of this stone. Among these are pink sapphires — coloured by traces of chromium —, yellow sapphires — due to iron in their structure —, or green sapphires, caused by the simultaneous presence of iron and chromium, resulting in a uniform tone throughout the stone. There are also purple sapphires, ranging from lavender to violet, black sapphires, recognisable by their opaque appearance and subtle sheen, and white sapphires, completely colourless, valued for their transparency and the clean way they allow light to pass through.

Within these precious stones is the star sapphire, a variety that displays an optical phenomenon known as asterism. When exposed to direct light, it shows a six-pointed star that appears to move across its surface. This effect is due to tiny needle-shaped rutile inclusions. The phenomenon is extremely rare, and some specimens from northern Thailand even present a golden-toned star. The most famous example is the Star of India, a dark blue sapphire of 563.35 carats with visible asterism on both sides, currently exhibited at the American Museum of Natural History in New York.

Some of the most famous sapphires in history

Several sapphires have earned a prominent place in history, whether for their size, origin, or exclusivity. Among them, the most famous is Princess Diana’s engagement ring, a piece with an 18-carat blue sapphire surrounded by diamonds. The jewel passed to Kate Middleton after her engagement to Prince William, becoming one of the most recognisable sapphires in the world.

In the British Royal Family, other notable pieces also stand out, such as Queen Victoria’s sapphire and diamond tiara, or the Prince Albert brooch, one of Queen Elizabeth II’s favourites.

Outside the monarchy, there are equally famous examples, such as the Bismarck sapphire necklace, designed by Cartier in 1935, featuring a 98.6-carat cornflower-blue sapphire from Sri Lanka, accompanied by 312 diamonds and nine additional sapphires. Another notable example is the Star of Bombay, a 182-carat star sapphire that actor Douglas Fairbanks gifted to his wife Mary Pickford.

Among historical jewels is also the Stuart Sapphire, weighing 104 carats, integrated into the British Crown Jewels and placed at the back of the Imperial State Crown.

Sapphire jewellery in Gibraltar

If you are looking for a place to acquire jewellery pieces adorned with sapphires in Gibraltar, at The Red House you will find a selection of exclusive pieces designed with high-quality sapphires in different tones, so you can find that essential piece for your jewellery box.