| Property | Obsidian | Onyx |
|---|---|---|
| Category | Semi-Precious Gems | Semi-Precious Gems |
| Primary Color | black | black |
| Mohs Hardness | 5.0–5.5 | 6.5–7.0 |
| Specific Gravity | 2.35 | 2.55 |
| Refractive Index | 1.45 | 1.53 |
| Crystal System | Amorphous | Trigonal |
| Luster | Vitreous | — |
| Chemical Formula | — | — |
| Price Tier | Budget (< $50/ct) | Moderate ($50-500/ct) |
| Daily Wear | いいえ | いいえ |
Key Differences
- ◆ {'gem_a': '5.0', 'gem_b': '6.5', 'property': 'Hardness (Mohs)'}
- ◆ {'gem_a': 'Amorphous', 'gem_b': 'Trigonal', 'property': 'Crystal System'}
- ◆ {'gem_a': '2.35', 'gem_b': '2.55', 'property': 'Specific Gravity'}
- ◆ {'gem_a': '1.45', 'gem_b': '1.53', 'property': 'Refractive Index'}
- ◆ {'gem_a': 'Vitreous', 'gem_b': 'N/A', 'property': 'Luster'}
- ◆ {'gem_a': 'budget', 'gem_b': 'moderate', 'property': 'Price Range'}
- ◆ {'gem_a': 'No', 'gem_b': 'No', 'property': 'Daily Wear'}
When to choose Obsidian
より手頃な価格を求める方にはオブシディアンがお勧めです。コレクターピースや特別な場面のジュエリーに向いています。
When to choose Onyx
傷つきにくさ・高い輝き・高品質を重視する方にはオニキスがお勧めです。婚約指輪や日常使いに最適です。
Frequently Asked Questions
Which is harder, Obsidian or Onyx?
Onyx is harder at 6.5-7.0 on the Mohs scale, compared to Obsidian at 5.0-5.5. This makes Onyx more resistant to scratching. Onyx requires more careful handling and is not ideal for daily wear, while obsidian requires more careful handling and is not ideal for daily wear.
Is Obsidian more expensive than Onyx?
No, Obsidian is generally less expensive. Obsidian is classified as budget-friendly (under $50/ct) at budget-friendly (under $50/ct), while Onyx is moderately priced ($50-500/ct) at moderately priced ($50-500/ct).
Should I choose Obsidian or Onyx for an engagement ring?
Neither Obsidian nor Onyx is ideal for an engagement ring worn daily. Onyx (6.5-7.0 Mohs) is the more durable of the two, while Obsidian (5.0-5.5 Mohs) is softer. If you choose either, consider a protective setting like a bezel.
How can I tell Obsidian and Onyx apart?
There are several visual cues: both appear black, but often in different saturations; Onyx (RI 1.53-1.543) shows more brilliance than Obsidian (RI 1.45-1.55); they have different crystal systems — Obsidian is Amorphous and Onyx is Trigonal. A gemologist can confirm identification using refractive index testing.
Why do Obsidian and Onyx look similar?
Obsidian and Onyx look similar because both gems display black hues.