Onyx vs Tourmaline
Onyx and Tourmaline are both popular gemstones that share a similar color palette. Tourmaline has a Mohs hardness of 7.0 compared to Onyx at 6.5, making Tourmaline the more durable option. Onyx is typically moderately priced while Tourmaline is moderately priced.
| Property | Onyx | Tourmaline |
|---|---|---|
| Category | Semi-Precious Gems | Semi-Precious Gems |
| Primary Color | black | various |
| Mohs Hardness | 6.5–7.0 | 7.0–7.5 |
| Specific Gravity | 2.55 | 2.85 |
| Refractive Index | 1.53 | 1.614 |
| Crystal System | Trigonal | Trigonal |
| Luster | — | Vitreous |
| Chemical Formula | — | — |
| Price Tier | Moderate ($50-500/ct) | Moderate ($50-500/ct) |
| Daily Wear | لا | نعم |
Key Differences
- ◆ {'gem_a': '6.5', 'gem_b': '7.0', 'property': 'Hardness (Mohs)'}
- ◆ {'gem_a': 'Trigonal', 'gem_b': 'Trigonal', 'property': 'Crystal System'}
- ◆ {'gem_a': '2.55', 'gem_b': '2.85', 'property': 'Specific Gravity'}
- ◆ {'gem_a': '1.53', 'gem_b': '1.614', 'property': 'Refractive Index'}
- ◆ {'gem_a': 'N/A', 'gem_b': 'Vitreous', 'property': 'Luster'}
- ◆ {'gem_a': 'moderate', 'gem_b': 'moderate', 'property': 'Price Range'}
- ◆ {'gem_a': 'No', 'gem_b': 'Yes', 'property': 'Daily Wear'}
When to choose Onyx
Choose Onyx when you want its unique color and character. It's ideal for occasional wear pieces and pendants.
When to choose Tourmaline
Choose Tourmaline when you want superior hardness and scratch resistance, higher brilliance and light performance, and suitability for daily wear. It's ideal for engagement rings and everyday jewelry.
Frequently Asked Questions
Which is harder, Onyx or Tourmaline?
Tourmaline is harder at 7.0-7.5 on the Mohs scale, compared to Onyx at 6.5-7.0. This makes Tourmaline more resistant to scratching. Tourmaline is suitable for daily wear, while onyx requires more careful handling and is not ideal for daily wear.
Is Onyx more expensive than Tourmaline?
Onyx and Tourmaline are in a similar price range, both classified as moderately priced ($50-500/ct). Onyx typically ranges moderately priced ($50-500/ct), while Tourmaline ranges moderately priced ($50-500/ct).
Should I choose Onyx or Tourmaline for an engagement ring?
For an engagement ring, Tourmaline is the stronger choice with a durability rating of 7/10. At 7.0-7.5 Mohs hardness, it can withstand daily wear well. Onyx (6.5-7.0 Mohs) is softer and more prone to scratching with everyday use, making it better suited for occasional-wear jewelry.
How can I tell Onyx and Tourmaline apart?
There are several visual cues: Onyx typically appears black while Tourmaline is various; Tourmaline (RI 1.614-1.666) shows more brilliance than Onyx (RI 1.53-1.543). A gemologist can confirm identification using refractive index testing.
Why do Onyx and Tourmaline look similar?
Onyx and Tourmaline look similar because both can show overlapping colors — Onyx is black and Tourmaline is various.