Jewelry IdentifierBlue Gemstones
The classic blue gemstones are sapphire, aquamarine, and blue topaz — with tanzanite, turquoise, and lapis lazuli close behind.
Blue in gemstones usually comes from iron, titanium, or copper. Sapphire is the benchmark, but many blue stones are mistaken for it. Here's how to identify a blue stone by hardness, transparency, and value.
| Blue gemstone | Hardness (Mohs) | What it is / how to spot it | Value |
|---|---|---|---|
| Sapphire | 9 | The benchmark blue gem — extremely hard corundum, from pale to deep 'royal' blue. | High |
| Aquamarine | 7.5–8 | Light sky-blue beryl, usually very clean and transparent. | Mid |
| Blue topaz | 8 | Bright blue and affordable; most is heat/irradiation-treated colorless topaz. | Low |
| Tanzanite | 6.5–7 | Violet-blue zoisite, found only in Tanzania; softer, so treat gently. | Mid–High |
| Turquoise | 5–6 | Opaque robin's-egg blue, often with a matrix; porous and soft. | Low–Mid |
| Lapis lazuli | 5–5.5 | Deep ultramarine rock flecked with gold pyrite; opaque. | Low |
| Blue zircon | 6.5–7.5 | Brilliant, high-dispersion blue — a natural stone, not cubic zirconia. | Low–Mid |
| Kyanite | 4.5–7 | Streaky sapphire-blue with hardness that varies by direction. | Low |
| Iolite | 7–7.5 | Violet-blue cordierite that shifts color when turned (pleochroism). | Low |
| Larimar | 4.5–5 | Soft, pale sky-blue pectolite found only in the Dominican Republic. | Low |
| Apatite | 5 | Neon 'Paraiba-like' blue-green; soft and rarely faceted for wear. | Low |
| Blue spinel | 8 | Hard, singly-refractive blue — historically confused with sapphire. | Mid |
How to identify your blue stone
Color alone won't confirm a gemstone — several blue stones look alike but differ in hardness, weight, and value. The fastest way to know what you have is to photograph it and run it through the free Gemstone Identifier, then confirm whether it's natural or a simulant with the Is It Real? tool. For what the piece is worth, get a free jewelry appraisal.
Frequently asked questions
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