Sapphire: The Benchmark for Blue Gemstones
Among blue gemstones, sapphire remains the standard against which many others are judged. Part of the corundum family, sapphire ranks second only to diamond in hardness, making it both durable and desirable.
The most prized blue sapphires display a rich, even saturation, often described as velvety or cornflower blue. While sapphires occur in a range of colours, blue remains the most sought-after.
For many collectors, the pinnacle is the Kashmir sapphire. Discovered in the late nineteenth century in the Himalayan region between modern-day India and Pakistan, these stones are renowned for their exceptional colour and rarity. The deposit was exhausted quickly, meaning genuine Kashmir sapphires are now encountered almost exclusively in historic jewellery. Today, provenance, colour and clarity continue to drive demand for fine sapphires at auction.
Sapphire vs Tanzanite: Can You Tell the Difference?
One of the most common identification challenges involves sapphire and Tanzanite. When viewed in isolation, both can display a rich blue colour and excellent transparency.
Recently, Lyon & Turnbull offered two rings of similar appearance: one set with a sapphire and the other with Tanzanite. While visually comparable, the sapphire achieved £13,750 including buyer's premium, while the Tanzanite sold for £7,375 including buyer's premium. The difference illustrates why accurate gemstone identification remains so important.
Tanzanite
Unlike sapphire, Tanzanite is a relatively recent discovery. Found only in Tanzania and introduced to the jewellery market in 1967, it was famously promoted by Tiffany & Co., who gave the stone its now-familiar name.
Tanzanite is known for a property called trichroism, meaning it can display different colours depending on the viewing angle. Blue, violet and hints of green may all be visible within a single stone.
The finest examples exhibit an intense blue colour with subtle violet undertones, which can bring them close in appearance to fine sapphires. However, Tanzanite is softer than sapphire and generally commands lower prices, despite its rarity.
Aquamarine: The Colour of Seawater
Aquamarine takes its name from the Latin for "seawater", a fitting description for its pale to medium blue tones.
Part of the beryl family, which also includes emerald and morganite, aquamarine is valued for its exceptional clarity. Unlike many coloured gemstones, high-quality aquamarines are often free from visible inclusions, making them particularly suited to emerald-cut and step-cut designs.
Aquamarine became especially fashionable during the Art Deco period and remained popular throughout the twentieth century. Cartier was among the jewellers who championed the stone, creating elegant aquamarine jewels that appealed to a growing market for coloured gemstones. Many of the finest aquamarines originate from Brazil, which continues to produce exceptional examples today.
Aquamarine vs Blue Topaz: Spotting the Difference
Aquamarine and blue topaz are perhaps the two blue gemstones most frequently confused with one another.
Their colours can overlap significantly, particularly when comparing pale aquamarines with Sky Blue topaz. Yet auction results often reveal substantial differences in value. In one recent comparison, an aquamarine and diamond pendant sold for £5,040 including buyer's premium, while a blue topaz and diamond pendant achieved £1,008.
Blue Topaz
Blue topaz is widely appreciated for its bright, attractive colour and affordability.
Three principal colour varieties are recognised:
- Sky Blue: pale and delicate
- Swiss Blue: bright and vivid
- London Blue: deep blue with grey undertones
Of these, London Blue is often the most sought after, while Sky Blue is most commonly mistaken for aquamarine.
Topaz has been used in jewellery for centuries and occurs in a wide variety of colours beyond blue, including yellow, pink and the highly prized Imperial Topaz.
