Gemstone Basics: A Quick Guide to Popular Gems

Your ultimate guide to gemstones, designed to help you understand their unique characteristics and compare them effectively.

Diamonds:

• Colour: Colourless to near-colourless (also available in various colours)

• Hardness: 10 on the Mohs scale (hardest gemstone)

• Clarity: Ideally free from inclusions

• Value: Highest value is driven by exceptional clarity, cut, carat weight, and the rarity of colourless diamonds; coloured diamonds are valued for their unique hues.

Emeralds:

• Colour: Pale green to a deep bluish shade

• Hardness: 7.5-8 on the Mohs scale

• Clarity: Typically contain natural inclusions visible to the unaided eye

• Value: High value is determined by the intensity of green colour and clarity; stones with fewer inclusions and a deep, even colour command higher prices.

Sapphires:

• Colour: Typically blue, but also available in a range of colours (excluding red)

• Hardness: 9 on the Mohs scale

• Clarity: Often have some inclusions

• Value: High value is associated with rich, intense blue hues and clarity; rare colours like pink and padparadscha sapphires also fetch higher prices.

Rubies:

• Colour: From near-burgundy to pale pink

• Hardness: 9 on the Mohs scale

• Clarity: Usually have inclusions as inclusion-free rubies are rare.

• Value: Highest value is linked to the depth and purity of red colour; rubies with fewer inclusions and a vibrant, clear colour are the most sought after.

Tanzanites:

• Colour: Blue to violet.

• Hardness: 6-7 on the Mohs scale

• Clarity: Some stones may have inclusions

• Value: High value is associated with deep blue-violet colours and high clarity; tanzanites with intense colour saturation are the most valuable.

Topaz:

• Colour: Available in a variety of colours including blue, pink, and yellow

• Hardness: 8 on the Mohs scale

• Clarity: Generally few eye-visible inclusions

• Value: Variable; high value for rare colours like imperial topaz (orange-pink) and for stones with excellent clarity and colour saturation.

Tourmalines:

• Colour: Wide range, including pink, green, blue, and more

• Hardness: 7-7.5 on the Mohs scale

• Clarity: Can be found with or without inclusions; often transparent

• Value: Variable; higher value for rare colours like Paraíba (neon blue-green) and for stones with good clarity and intense colour.

Citrines:

• Colour: Yellow to golden brown

• Hardness: 7 on the Mohs scale

• Clarity: Generally clear, with few inclusions

• Value: Generally more affordable; higher value for deeper, more intense yellow or orange hues and stones with excellent clarity.

Garnets:

• Colour: Available in various colours including red, green, and orange

• Hardness: 6.5-7.5 on the Mohs scale

• Clarity: Clarity varies by garnet type; red garnets typically have few to no eye-visible inclusions, while some orange garnets may exhibit visible inclusions.

• Value: Variable; higher value for rare colours like demantoid (green) and for stones with vibrant colour and high clarity.

Amethysts:

• Colour: Purple, ranging from light lavender to deep violet

• Hardness: 7 on the Mohs scale

• Clarity: Typically clear of eye-visible inclusions

• Value: Generally more affordable; higher value for stones with a deep, even purple colour and good clarity.

Opals:

• Colour: Displays a play-of-colour with various hues

• Hardness: 5.5-6 on the Mohs scale

• Clarity: Generally translucent to opaque

• Value: Can be high, particularly for opals with vibrant, multi-colour play-of-colour and high-quality patterns.