Lab-Grown Coloured Gemstones: Sapphires, Rubies and Emeralds Explained

Lab-grown diamonds get most of the headlines, but the lab-grown story is just as significant — and in some cases more so — for coloured gemstones. For sapphires and rubies in particular, the gap between lab-grown and natural pricing is extraordinary, and the case for lab-grown is straightforwardly compelling for buyers who want colour rather than geological provenance.

What "lab-grown" means for coloured gemstones

The term "lab-grown" describes any gemstone grown in a laboratory using controlled processes that replicate the conditions under which natural gems form. It is not the same as "simulant": a simulant (blue glass, cubic zirconia, spinel) merely resembles the target gemstone but is a chemically different material. A lab-grown sapphire is chemically aluminium oxide with trace colouring elements — the same as a mined sapphire.

Lab-grown coloured gemstones have been produced commercially since the late 19th century. Auguste Verneuil patented the first practical method for growing synthetic ruby in 1902. The technology has advanced enormously since then — modern hydrothermal methods (which grow crystals slowly from hot solution under pressure, mimicking how natural gems form in hydrothermal veins) produce material that closely resembles the best natural stones.

The three key gemstones

Lab-grown sapphire

Sapphire is corundum (aluminium oxide) coloured by trace amounts of iron and titanium (blue), chromium (pink/padparadscha), or other elements (yellow, orange, green). The lab produces the same mineral in the same crystal structure.

Why lab-grown sapphire makes particular sense: Fine natural blue sapphires — particularly unheated Burmese or Ceylon (Sri Lankan) origin stones — are among the rarest and most expensive coloured gems per carat. A 2ct unheated Burmese blue sapphire of genuine cornflower-blue colour can cost £8,000–£25,000 per carat. A lab-grown blue sapphire of equivalent colour and transparency costs approximately £30–£80 per carat.

At Mohs 9 hardness, sapphire is also one of the most durable gemstones for daily wear — only diamond is harder among common gemstones. A lab-grown sapphire in an engagement ring will last as long as a natural one; the wear characteristics are identical.

Lab-grown ruby

Ruby is the red variety of corundum — the same mineral as sapphire, coloured by chromium. Natural fine rubies (particularly pigeon-blood Burmese rubies without heat treatment) are exceptionally rare and correspondingly expensive. A natural 1ct pigeon-blood ruby with a major laboratory certificate (Gübelin, GRS) can be the most expensive gemstone per carat on the retail market — more expensive than comparable diamonds.

Lab-grown rubies are produced by the Verneuil, flux, or hydrothermal methods. High-quality hydrothermal lab-grown rubies can be very beautiful and essentially indistinguishable from natural rubies without laboratory analysis. At approximately £20–£60 per carat, they are accessible in sizes that would be financially impossible in natural form.

The caveat for ruby buyers: the colour specification matters enormously. "Red" covers a very wide range in corundum — from orange-red to pink-red to brownish-red to the pure vivid red of the finest Burmese origin. When sourcing lab-grown ruby, we specify colour temperature and saturation to get the exact tone our customers want.

Lab-grown emerald

Emerald is beryl (beryllium aluminium silicate) with chromium and vanadium creating the green colour. Natural emeralds are almost universally heavily included — so much so that the presence of inclusions (called "jardin") is considered normal rather than a defect, and most natural emeralds are oil-treated or resin-filled to improve their apparent clarity.

Lab-grown emeralds are produced by flux or hydrothermal methods. Hydrothermal lab-grown emeralds can be genuinely beautiful — good green saturation, fewer fractures than natural material, and no oil treatment. The colour profile of high-quality lab-grown emeralds closely matches fine Colombian natural emeralds.

One consideration for emerald rings: at Mohs 7.5–8, emerald is softer than sapphire or ruby and more prone to damage in daily-wear rings. This is true for both natural and lab-grown emeralds. A bezel or protective setting is worth considering for any emerald used in a ring worn every day.

The naming and disclosure issue

The jewellery industry has had a contested relationship with disclosure around lab-grown coloured gemstones, partly because the terms have changed over decades. "Synthetic" is the technically correct term but carries consumer connotations of inferiority. "Lab-created" and "lab-grown" are both used and both accurate.

We disclose clearly on every piece we sell: any lab-grown stone is identified as such in our documentation. You will always know what you're buying from us. If a seller won't confirm whether a stone is natural or lab-grown, that is a reason to look elsewhere.

Practical advice for buyers

For a large blue sapphire: Lab-grown is a genuinely excellent choice. The visual result at meaningful size (2ct+) is beautiful and the saving is dramatic. If you specifically want certified natural origin (for rarity, provenance or future resale), natural stones are available — but expect to pay a premium commensurate with their scarcity.

For a ruby ring: Lab-grown opens up a size range that simply isn't realistic for most people's budgets in natural form. The colour specification is key — come in and look at stones rather than ordering from a description.

For an emerald ring: Lab-grown hydrothermal is a strong choice for clarity; protect the stone with the right setting. If you love the included, organic look of natural emeralds, natural material is also available and provides a different (and to some people, more beautiful) character.

All three gemstones are available to us through our supplier network in both natural and lab-grown form. Come in to 7 Murray Place, Stirling, to see examples and discuss what suits your commission. Call 01786 462799 to book an appointment.