Gemstones are the result of precise geological conditions acting over immense periods of time. Their value and suitability for fine jewellery are determined by mineral composition, crystal structure, optical performance, durability and provenance. In high jewellery, these scientific attributes are inseparable from rarity, beauty and craftsmanship.
Diamond
Mineral: Carbon
Crystal System: Cubic (Isometric)
Hardness: 10 (Mohs)
Optical Properties: Very high refractive index, strong dispersion (fire)
Colour Varieties: Colourless; Fancy Yellow, Brown, Blue, Pink, Green, Orange, Red
Primary Origins: Botswana, South Africa, Namibia, Angola, Canada, Russia
Key Traits: Ultimate hardness, unmatched brilliance, exceptional wear resistance
Diamonds exhibit superior optical performance and durability, making them the benchmark gemstone for both technical excellence and enduring value.
Ruby
Mineral: Corundum (Aluminium Oxide)
Crystal System: Trigonal
Hardness: 9 (Mohs)
Optical Properties: Strong dichroism, high saturation
Colour Varieties: Pinkish red to deep purplish red
Primary Origins: Myanmar (Burma), Mozambique, Sri Lanka, Thailand
Key Traits: Rare vivid colour, excellent durability, high intrinsic value
Rubies owe their colour to chromium and are among the most valuable coloured gemstones when colour and transparency align.
Sapphire
Mineral: Corundum (Aluminium Oxide)
Crystal System: Trigonal
Hardness: 9 (Mohs)
Optical Properties: High brilliance, pleochroism
Colour Varieties: Blue, Pink, Yellow, Green, Purple, Orange, White, Padparadscha
Primary Origins: Sri Lanka, Madagascar, Myanmar, Kashmir, Australia
Key Traits: Exceptional durability, broad colour spectrum
Sapphires combine technical resilience with chromatic versatility, making them a cornerstone of high jewellery design.
Emerald
Mineral: Beryl
Crystal System: Hexagonal
Hardness: 7.5–8 (Mohs)
Optical Properties: Moderate brilliance, rich body colour
Colour Varieties: Bluish green to pure green
Primary Origins: Colombia, Zambia, Brazil
Key Traits: Intense colour, characteristic inclusions
Emeralds are celebrated for colour rather than clarity; inclusions are intrinsic and contribute to each stone’s identity.
Spinel
Mineral: Magnesium Aluminium Oxide
Crystal System: Cubic
Hardness: 8 (Mohs)
Optical Properties: High brilliance, single refraction
Colour Varieties: Red, Pink, Blue, Purple, Grey, Black
Primary Origins: Myanmar, Sri Lanka, Tanzania, Vietnam
Key Traits: Stable colour, typically untreated
Modern appreciation of spinel centres on its natural colour integrity and excellent durability.
Aquamarine
Mineral: Beryl
Crystal System: Hexagonal
Hardness: 7.5–8 (Mohs)
Optical Properties: High clarity, subtle brilliance
Colour Varieties: Pale blue to blue‑green
Primary Origins: Brazil, Nigeria, Madagascar, Mozambique
Key Traits: Transparent crystals, refined tonal elegance
Aquamarine’s colour is caused by iron and is often gently heat enhanced to refine hue.
Tourmaline
Mineral Group: Complex Borosilicates
Crystal System: Trigonal
Hardness: 7–7.5 (Mohs)
Optical Properties: Strong pleochroism
Colour Varieties: Pink, Green, Blue (Indicolite), Red (Rubellite), Yellow, Black, Bi‑colour, Paraíba
Primary Origins: Brazil, Mozambique, Nigeria, Afghanistan
Key Traits: Exceptional colour diversity, distinctive optics
Tourmaline is unrivalled in chromatic range, offering designers rare expressive freedom.
Garnet
Mineral Group: Silicates
Crystal System: Cubic
Hardness: 6.5–7.5 (Mohs)
Optical Properties: Good brilliance, no pleochroism
Colour Varieties: Red, Green, Orange, Yellow, Purple
Primary Origins: Tanzania, Kenya, Sri Lanka, India, Madagascar
Key Traits: Rich colour, variable durability by species
Garnets comprise multiple species, each with distinct chemistry and performance characteristics.
Topaz
Mineral: Aluminium Fluorosilicate
Crystal System: Orthorhombic
Hardness: 8 (Mohs)
Optical Properties: High clarity, strong polish
Colour Varieties: Colourless, Blue, Yellow, Pink, Imperial
Primary Origins: Brazil, Pakistan, Russia, Nigeria
Key Traits: Excellent brilliance, cleavage sensitivity
Topaz demands expert setting due to its perfect cleavage despite strong surface hardness.
Amethyst
Mineral: Quartz
Crystal System: Trigonal
Hardness: 7 (Mohs)
Optical Properties: Moderate brilliance, colour zoning
Colour Varieties: Light lilac to deep purple
Primary Origins: Brazil, Uruguay, Zambia
Key Traits: Stable colour, reliable durability
Amethyst derives its colour from iron and natural irradiation within the crystal lattice.
Technical Excellence in Fine Jewellery
In high jewellery, gemstone selection extends beyond aesthetics to encompass optical performance, structural integrity and provenance. A deep understanding of these scientific principles ensures each gemstone is not only beautiful, but enduring, rare and worthy of its place within fine jewellery.
