Sapphire Stability Types Explained: Why Type 3a Can Be a Hidden Advantage
- Caram
- Aug 11
- 3 min read
In the world of fine gemstones, few topics create as much quiet confusion — even among seasoned dealers — as color stability classifications. Introduced by laboratories like GRS to help buyers understand how a stone might react to light exposure over time, these classifications can actually provide deep insights into a sapphire’s natural beauty. But only if they’re interpreted correctly.
At Caram, we believe in empowering our clients through education. One topic we’re frequently asked about — and one we often find ourselves clarifying even for trade professionals — is the meaning of the so-called “Type 3” classifications, especially Type 3a.
Let’s explore what this really means — and why, far from being a red flag, it can be a bonus for buyers.
What is a Sapphire Stability Type?
Color stability tests are conducted to evaluate how a gemstone’s color may change when exposed to light. This is particularly relevant for sapphires in the orange to yellow spectrum, including the beloved Padparadscha sapphire, which is prized for its delicate balance of pink and orange hues.
Some sapphires may appear to fade slightly under certain types of lighting — but in most cases, this is a reversiblephenomenon. Just as some colors may fade, others may actually intensify when re-exposed to UV or sunlight. This behavior is what labs are testing for when assigning a sapphire stability type classification.

The GRS Sapphire Stability Classifications (Types 1-4)
According to GRS' color stability types, stones tested for color stability are classified from Type 1 to Type 4, each reflecting how the color reacts to light exposure:
Type 1: Fully stable — no change in color expected.
Type 2a and 2b: Some fading may occur, but the padparadscha color is still visible in at least one state.
Type 3a and 3b: Here’s where things get interesting — the stone may gain intensity when exposed to UV or sunlight.
Type 4: Color may fade, and it won’t come back with UV exposure.
The key point? Type 3a does not mean the color will fade. In fact, it suggests quite the opposite.
Type 3a Sapphires: Misunderstood and Undervalued
Many buyers — and some sellers — assume that a Type 3a classification is a warning sign. It’s often misinterpreted as an indication that the color will “fade” over time. But according to GRS, what it actually means is this:
The stone may have been submitted to the lab in a discharged state (e.g., after prolonged indoor lighting). When exposed to UV light or natural sunlight, its color saturation can increase.
In other words, if you’re buying a Type 3a sapphire, you’re effectively buying it at its baseline. The best is yet to come. There’s no downside risk — only potential upside in color intensity. That’s not a flaw. It’s a feature.
Why This Matters for Buyers
For collectors and connoisseurs, understanding these classifications is essential. But even more essential is having a trusted advisor who can interpret them in context.
Because ultimately, a color stability type is only one piece of the puzzle. The stone’s origin, treatment status, cut, clarity, and most importantly — how it looks in real life — are all part of the bigger picture.
At Caram, we don’t just read lab reports. We read between the lines.
A Final Word
The color stability classification system is a valuable tool, but like any tool, it’s only as useful as the expertise behind it. Misunderstandings about terms like “Type 3a” can lead to hesitation — or missed opportunities. Our advice? Don’t be afraid of the fine print. Ask questions. And most importantly, work with a trusted gemstone dealer who understands the nuance.
Because the difference between a good purchase and a great one is often just a matter of understanding what you’re truly looking at.
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Interested in learning more about gemstone reports and how to read them? Reach out to our team at Caram. We’re always happy to share what we know — and help you discover the extraordinary.
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