Moonstone vs Opal
Comparing Moonstone and Opal — two gemstones with a strikingly similar appearance. On the Mohs scale, Moonstone rates 6.0 and Opal rates 5.0. In terms of price, Moonstone falls in the moderately priced range and Opal in the budget-friendly range.
| Property | Moonstone | Opal |
|---|---|---|
| Category | Semi-Precious Gems | Semi-Precious Gems |
| Primary Color | white | white |
| Mohs Hardness | 6.0–6.5 | 5.0–6.5 |
| Specific Gravity | 2.56 | 1.98 |
| Refractive Index | 1.518 | 1.37 |
| Crystal System | Monoclinic | Amorphous |
| Luster | Vitreous | — |
| Chemical Formula | — | — |
| Price Tier | Moderate ($50-500/ct) | Budget (< $50/ct) |
| Daily Wear | No | No |
Key Differences
- ◆ {'gem_a': '6.0', 'gem_b': '5.0', 'property': 'Hardness (Mohs)'}
- ◆ {'gem_a': 'Monoclinic', 'gem_b': 'Amorphous', 'property': 'Crystal System'}
- ◆ {'gem_a': '2.56', 'gem_b': '1.98', 'property': 'Specific Gravity'}
- ◆ {'gem_a': '1.518', 'gem_b': '1.37', 'property': 'Refractive Index'}
- ◆ {'gem_a': 'Vitreous', 'gem_b': 'N/A', 'property': 'Luster'}
- ◆ {'gem_a': 'moderate', 'gem_b': 'budget', 'property': 'Price Range'}
- ◆ {'gem_a': 'No', 'gem_b': 'No', 'property': 'Daily Wear'}
When to choose Moonstone
Choose Moonstone when you want superior hardness and scratch resistance, higher brilliance and light performance, and premium quality and rarity. It's ideal for occasional wear pieces and pendants.
When to choose Opal
Choose Opal when you want a more budget-friendly price point, and its significance as the modern October birthstone. It's ideal for collector specimens and carefully worn jewelry.
Frequently Asked Questions
Which is harder, Moonstone or Opal?
Moonstone is harder at 6.0-6.5 on the Mohs scale, compared to Opal at 5.0-6.5. This makes Moonstone more resistant to scratching. Moonstone requires more careful handling and is not ideal for daily wear, while opal requires more careful handling and is not ideal for daily wear.
Is Moonstone more expensive than Opal?
Yes, Moonstone is generally more expensive. Moonstone is classified as moderately priced ($50-500/ct) with prices around moderately priced ($50-500/ct), while Opal is budget-friendly (under $50/ct) at budget-friendly (under $50/ct).
Should I choose Moonstone or Opal for an engagement ring?
Neither Moonstone nor Opal is ideal for an engagement ring worn daily. Moonstone (6.0-6.5 Mohs) is the more durable of the two, while Opal (5.0-6.5 Mohs) is softer. If you choose either, consider a protective setting like a bezel.
How can I tell Moonstone and Opal apart?
There are several visual cues: both appear white, but often in different saturations; Moonstone (RI 1.518-1.527) shows more brilliance than Opal (RI 1.37-1.52); they have different crystal systems — Moonstone is Monoclinic and Opal is Amorphous. A gemologist can confirm identification using refractive index testing.
Is Moonstone a good alternative to Opal?
Moonstone is actually more expensive than Opal, so it functions as a premium upgrade rather than an alternative. Moonstone is moderately priced ($50-500/ct) versus Opal at budget-friendly (under $50/ct). If budget is a concern, Opal offers a similar look at a lower price.