Amethyst vs. Purple Sapphire: A Gemstone Comparison

This might not be the most obvious gemstone pairing to look at, but I recently came across a lab-grown purple sapphire tucked into a quartz bundle, so I figured it was the perfect excuse to do a comparison.

Amethyst and Purple Sapphire are two captivating purple gemstones, often chosen for their rich, regal hues and timeless appeal. While they can look similar at first glance, these stones differ significantly in terms of mineral composition, durability, and even how they’re perceived in the gemstone world.

Amethyst has long been prized as a 'semi-precious' gemstone, once considered as valuable as ruby or emerald until large deposits were discovered. Purple Sapphire, on the other hand, belongs to the corundum family, one of the most durable and precious gemstone families, and is far rarer in its purple form.

Let’s explore the key differences between Amethyst and Purple Sapphire, from their visual traits to their spiritual associations.

How to Tell the Difference: Visual & Gemmological Tests

Visual Clues

Amethyst: Typically shows a light to deep violet or purple colour, often with slight zoning or uneven saturation. Some stones may have reddish or bluish undertones. Eye clean examples are common, especially in faceted stones.

Purple Sapphire: Displays a more saturated, often darker purple, sometimes with pink or bluish secondary tones. Its brilliance is usually higher due to its superior hardness and refractive index. Stones are often cut to maximise brilliance rather than size.

Gemmological Tests

Colour

Amethyst: Ranges from light lavender to deep royal purple. Some stones may exhibit “Siberian” colour (deep purple with flashes of red or blue). Colour zoning is common.

Purple Sapphire: Typically a more intense, saturated purple that may lean slightly pinkish or bluish depending on the trace elements present. 

Clarity & Inclusions

Amethyst: Type 2 clarity and while this means they are ususally included, it's not uncommon to find eye clean examples. When present, inclusions are often feathers or minor liquid inclusions.

Purple Sapphire: Also type 2 clarity and while eye clean examples are available, they are less common and do demand higher prices. When present, inclusions are usually silk (rutile needles), fingerprints, or crystals of other minerals. 

Gemstone Formation

Amethyst: A purple variety of quartz, formed in volcanic rocks and hydrothermal veins. Found in Brazil, Uruguay, Africa, and Russia.

Purple Sapphire: A variety of corundum, formed under high-pressure and high-temperature conditions in metamorphic or igneous rocks. Sourced from Sri Lanka, Madagascar, Myanmar, and parts of East Africa.

Durability & Wearability

Scratch Resistance (Mohs Hardness Scale):

• Amethyst: 7 (Generally considered good for daily wear)
• Purple Sapphire: 9 (extremely durable, ideal for everyday jewellery, including engagement rings)

Cleavage & Toughness:

• Amethyst: No cleavage, but moderate toughness. Can chip if struck.
• Purple Sapphire: No true cleavage and excellent toughness. Handles wear and tear extremely well.

Best Use:
Amethyst is perfect for pendants, earrings, and rings, but rings should be removed when doing heavy activity to protect the stone. Purple Sapphire is suitable for everyday rings, bracelets, or any jewellery meant to last a lifetime.

Enhancements & Treatments

Amethyst: Amethyst isn't always treated, but it is quiet common to heat lighter stones to either deepen their purple tones or to change their colour to either yellow (citrine) or green (Prasiolite).

Purple Sapphire: May be heat treated to improve colour and clarity. This is common and accepted in the trade. Untreated stones, especially with vivid colour, command a premium. Some diffusion-treated stones exist, but reputable sellers disclose this clearly.

Price Comparison

Amethyst: Readily available and affordable. Prices typically range from £5 to £50 per carat, depending on size, clarity, and origin.

Purple Sapphire: Far more valuable and rare. Prices can range from £50 to £1,600+ per carat, depending on quality, treatment status, and origin.

Size

Amethyst: Amethyst is widely available in a broad range of sizes, from tiny melee stones under 1mm to impressive centrepieces over 20 carats. Larger amethyst gemstones are relatively common and affordable, making them a popular choice for bold jewellery designs. 

Purple Sapphire: Purple sapphire is far rarer in large sizes. Most faceted stones on the market range from under 1 carat to around 3 carats, especially for high-quality gems with strong colour and clarity.

Rarity & Sourcing

Amethyst: Abundant and mined globally. Not considered rare, though exceptional specimens from Siberia or Uruguay are more prized.

Purple Sapphire: Much rarer, especially in untreated form. Found in fewer locations, with Madagascar and Sri Lanka being key sources for top-quality material.

Cut & Shape Preferences

Amethyst: Commonly cut into ovals, rounds, emerald cuts, and fantasy shapes due to its affordability. Popular for creative and oversized cuts.

Purple Sapphire: Typically cut to maximise brilliance. Most often seen in oval, cushion, and round cuts. Cutting usually prioritises colour and sparkle over carat retention.

Symbolic & Spiritual Associations

Amethyst: Associated with peace, protection, and purification. Believed to calm the mind and aid in meditation. A favourite among spiritual practitioners.

Purple Sapphire: Linked to Intuition, Spiritual Wisdom, and Transformation. Said to enhance focus, inner peace, and open the mind to divine truths.

Comparison Summary

Amethyst and Purple Sapphire are both gorgeous purple gemstones, but their uses and values differ dramatically.

If you’re looking for a luxurious, durable, and investment-worthy purple stone, Purple Sapphire is a top-tier choice. But if you prefer an affordable, widely available gemstone with peaceful energy and rich colour, Amethyst is a wonderful option, especially for large statement pieces.

Whichever you choose, each stone brings its own unique look to your jewellery designs.