Comparison · Semi-Precious Stones vs Minerals
Aquamarine vs Tourmaline
Aquamarine and Tourmaline are easy to confuse. Both sit near Mohs 7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Aquamarine and Tourmaline
- Both sit near Mohs 7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Aquamarine leaves a white streak on unglazed porcelain, Tourmaline leaves white (colorless).
- Hold a thin edge to the light: Aquamarine is transparent, Tourmaline is Transparent to opaque.
- They overlap in blue and green, but Tourmaline also comes in black, pink, and multicolored.
- Well-formed crystals give it away: Aquamarine is hexagonal, Tourmaline is Trigonal.
Aquamarine vs Tourmaline properties
| Property | Aquamarine | Tourmaline |
|---|---|---|
| Type | Semi-Precious Stones | Minerals |
| Mohs hardness | 7.5 | 7–7.5 |
| Luster | vitreous | Vitreous |
| Streak | White | White (colorless) |
| Transparency | transparent | Transparent to opaque |
| Specific gravity | 2.7 | 3.0–3.25 |
| Crystal system | hexagonal | Trigonal |
| Common colors | Light Blue, Blue-Green, Greenish Blue | Black, Green, Pink, Blue, Multicolored (watermelon) |
| Rarity | uncommon | common |
| Typical specimen value | $50–$5000+ | $2–$150+ |
Which is more valuable?
Aquamarine is usually the more valuable of the two: a typical collector specimen runs about $300 against $20 for Tourmaline, and premium Aquamarine can reach $5000 or more.
About Aquamarine
Aquamarine is a blue variety of beryl, the same mineral family as emerald. Its name means 'water of the sea' in Latin.
About Tourmaline
Tourmaline is not a single mineral but a group of complex borosilicates sharing a trigonal crystal structure and the general formula XY3Z6(BO3)3Si6O18(OH)4, with composition varying widely among species such as schorl, elbaite, and dravite. It has the widest color range of any mineral group, from jet-black schorl to multicolored elbaite crystals that can shift from pink to green along a single crystal, called watermelon tourmaline. It is also both piezoelectric and pyroelectric, generating an electric charge under pressure or heat.
Aquamarine vs Tourmaline FAQ
Is Aquamarine the same as Tourmaline?
No. Aquamarine is a semi-precious stone while Tourmaline is a mineral. Both sit near Mohs 7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Aquamarine from Tourmaline?
Both sit near Mohs 7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Aquamarine leaves a white streak on unglazed porcelain, Tourmaline leaves white (colorless). Hold a thin edge to the light: Aquamarine is transparent, Tourmaline is Transparent to opaque.
Which is harder, Aquamarine or Tourmaline?
They are about equally hard, both near Mohs 7.5.
Which is more valuable, Aquamarine or Tourmaline?
Aquamarine is usually the more valuable of the two: a typical collector specimen runs about $300 against $20 for Tourmaline, and premium Aquamarine can reach $5000 or more.
