Are coloured lab-grown diamonds stable, and do their colours fade?

ZKZ Editorial TeamMain answer · Product & gemmology desk

We could not verify how stable the colour of any particular coloured lab-grown diamond is in daily wear, and we make no promise of permanence. What we can say is that colour in a diamond is caused by trace elements and defects, that colour may be altered by treatment after growth, and that a laboratory report can state whether treatment was applied.

What we verified

Fact GIA says trace elements and other imperfections in the diamond lattice cause colour and ultraviolet fluorescence in diamonds, and that these can be added by treatment or by synthesis in a laboratory.

Fact GIA says its Laboratory-Grown Colored Diamond Report includes a full quality assessment, a plotted clarity diagram and an assessment of growth type and post-growth treatment.

Fact The FTC Jewelry Guides (16 CFR 23.24) say it is unfair or deceptive to fail to disclose that a gemstone has been treated if the treatment is not permanent or has a significant effect on the stone's value.

What to ask

1. Is the colour as grown, or was the stone treated after growth?
2. Does the report say what the treatment was?
3. Does the seller offer a return if the colour changes?

Our advice Ask for a report that states growth type and post-growth treatment, and keep it.

It depends Whether a colour is stable depends on its cause and on any treatment, which differ from stone to stone.

Simple precautions

Our advice Keep the piece away from heat, such as a hair dryer or a hot car, and from harsh cleaners until you know the stone's treatment status. Take photographs when it is new, in the same light each time. If you see a change, contact the seller promptly with the photos, since evidence from the start makes any claim easier.

Our advice Keep the report with the piece. If colour ever seems to change, a dated report and photographs make it much easier to talk to the seller or a laboratory about what you are seeing.

Uncertain We did not find a verified study on colour change or fading for coloured lab-grown diamonds under heat, light or cleaning, so we say nothing on the likelihood. Follow the seller's care guidance.

Related reading: Can a Lab-Grown Diamond Pass a Diamond Tester? · Coloured Lab Grown Diamonds: Pink, Blue, Yellow and Beyond

Sources

• GIA 4Cs, Diamond types
• GIA, Laboratory-grown diamond services
• 16 CFR 23.24, FTC Jewelry Guides: disclosure of treatments to gemstones

Fact = stated by the cited source. Our advice = editorial recommendation. Uncertain / it depends = limits of what can be said in general.