The World of Natural Coloured Gemstones

The Mohs scale is a measure of a mineral's resistance to scratching, running from 1 (talc) to 10 (diamond). For jewellery purposes, it gives a rough guide to how well a stone will hold its surface finish over years of wear. Sapphire and ruby sit at Mohs 9, which means almost nothing in everyday life will scratch them. Opal sits at 5 to 6.5, which means sand, concrete, and other hard surfaces can mark it. Hardness is not the only measure of durability — toughness (resistance to breaking and chipping) matters too, which is why we also discuss cleavage, brittleness, and setting design when helping you choose a stone for an everyday ring.

Sapphire is our most recommended coloured stone for engagement rings, primarily because of its Mohs 9 hardness, its extraordinary colour range, and the fact that Australian parti and teal sapphires offer something genuinely original. Ruby shares sapphire's hardness and is an equally excellent choice. Beyond corundum, topaz, aquamarine, emerald, and morganite are all possible with the right setting design and an honest conversation about care. The best choice depends on your lifestyle, aesthetic preferences, and how you plan to care for the ring — which is exactly what our consultation is for.

Almost all of them, yes. Inclusions in emerald are so expected and accepted that the French term jardin — garden — is used affectionately to describe them. The internal landscape of an emerald is part of what makes it an emerald: the nature of its formation means that completely clean stones are extraordinarily rare and command prices that reflect that rarity. When we assess emeralds, we look at whether the inclusions affect structural integrity and whether they compromise the colour and life of the stone, rather than expecting perfection that the natural world rarely provides.

Treatments are very common in the coloured gemstone trade and most are entirely stable and accepted. Heat treatment of sapphires and rubies has been practised for centuries and produces permanent improvements to colour and clarity. Oiling and resin filling of emeralds is standard practice, though the degree of filling varies and should be disclosed. What matters is not whether a stone has been treated, but whether the treatment has been honestly disclosed and whether it affects the stone's long-term durability. We disclose all treatments on every stone we sell, and we are happy to discuss what this means in practical terms for any specific stone you are considering.

Opal can be used in an engagement ring, but it requires an honest conversation about the stone's nature and the wearer's lifestyle. At Mohs 5 to 6.5, opal will scratch more readily than most gemstones and is sensitive to impact, dryness, and household chemicals. For someone who works with their hands, or who is not comfortable removing jewellery before activity, we would not recommend opal as their primary stone. For someone who understands and embraces the stone's nature — and who is drawn to its extraordinary character — opal can be a deeply personal and beautiful choice. We would design the setting with maximum protection and have a frank conversation about care from the beginning.

Yes, and we encourage it. For stones of significant value, we prefer that you see and assess the stone in person before we proceed to setting. We can show you stones in different lights — natural daylight, incandescent, LED — because coloured gemstones can look substantially different under different light sources, and the one that moves you in your kitchen at home is the one that matters. We also offer a gemstone home trial program for certain stones, which allows you to live with a stone in your own environment before making the final decision.

Blue topaz and aquamarine are often compared because both are blue, both are transparent, and both are frequently used in jewellery. They are different minerals with different properties. Aquamarine is beryl — the same mineral family as emerald and morganite — and its blue colour is entirely natural. Blue topaz is usually colourless topaz that has been irradiated and heat-treated to produce its blue colour; this treatment is permanent and stable. Aquamarine tends toward softer, more nuanced blues with greenish undertones, while blue topaz can achieve a cleaner, more intense blue. Aquamarine is generally more expensive than treated blue topaz of equivalent size. The right choice depends on the colour and character you want.

Yes. Australian sourcing is one of the things we take most seriously. We source parti sapphires and teal sapphires from Queensland and New South Wales directly, and we work with established Australian opal suppliers at Lightning Ridge and Coober Pedy. If you want a piece that tells an entirely Australian story — stone, metal, and maker — that is something we are uniquely placed to deliver. We can also source other Australian stones on request: chrysoprase from Queensland, Australian garnet, and other regional specialities. Please ask us about specific requirements in your consultation.