Beyond the Diamond: An Introduction to Gemstones

Precious Versus Semi-Precious: A Useful, Imperfect Label

The terms "precious" and "semi-precious" are a holdover from older trade classifications rather than a strict measure of quality. In practice, diamonds, rubies, sapphires and emeralds are the four stones most commonly grouped as precious, largely due to their historical rarity, hardness and demand.

Many so-called semi-precious stones, such as fine aquamarine or tanzanite — itself mined exclusively in nearby Tanzania and a popular choice among our southern African clients — can be every bit as beautiful and, depending on size and quality, comparably valuable.

Hardness Matters More Than People Realise

Gemstone durability is measured using the Mohs scale, which ranks hardness from 1 to 10. Diamond sits at the very top at 10, which is part of why it has remained the default choice for a ring worn every day.

Sapphire, Ruby and Emerald: The Coloured Classics

Sapphires occur naturally in almost every colour beyond their famous blue, including pink and the softer pastel tones popular in modern design, and are available more readily in larger carat sizes than rubies.

Rubies are genuinely rare above one carat, which keeps prices high relative to size; for comparison, even a fancy red diamond, one of the rarest diamond colours that exists, is still typically less expensive than a ruby of equivalent quality.

Emeralds are usually cut into a rectangular, step-cut shape specifically to suit their natural crystal structure, and because the stone is less dense than diamond, an emerald of a given carat weight will generally look larger across the finger.

Lighter, More Affordable Options

Aquamarine offers an icy, pale blue tone, is usually eye-clean (free of visible inclusions), and sits at a respectable 7.5–8 on the Mohs scale, making it a durable choice for those drawn to a softer palette.

Amethyst, while only a 7 on the same scale and therefore less suited to constant daily knocks, remains a popular choice for statement pieces thanks to its rich purple tone and accessible price point regardless of size.

Lab-Grown Gemstones: Identical Chemistry, More Accessible Pricing

Lab-grown sapphires, rubies and emeralds are chemically and optically identical to their mined counterparts, grown under conditions engineered to replicate the same natural process over a far shorter timeframe. Specialist equipment is required to distinguish between a lab-grown and mined stone of the same type; the difference is invisible to the naked eye.