Sapphire
- Mineral
- Corundum
- Known For
- Rich blue color
- Mohs Hardness
- 9
- Regular Wear
- Excellent
Gemstone Education
Color, Character.
& Origin.
Every gemstone has its own character. Explore the color, composition, durability and distinctive qualities of sapphire, emerald, ruby and alexandrite — and discover which stone feels right for you.
01
Sapphire
Sapphire belongs to the corundum mineral family and is known for its rich color and remarkable hardness. Blue remains its most recognized expression, ranging from vivid tones to deep, saturated shades.
What Is It?
Sapphire is a variety of corundum valued for strength, clarity and distinctive color.
Color
Blue sapphire ranges from brighter vivid blue to deeper and more saturated tones.
Durability
With a Mohs hardness of 9, sapphire provides excellent resistance to scratching.
Lab-Grown
Lab-grown sapphire shares the essential mineral composition of natural sapphire with a different origin.
02
Emerald
Emerald is the green variety of beryl, admired for its distinctive color and visual character. Tone, saturation and clarity all contribute to the individual appearance of an emerald.
What Is It?
Emerald is the green variety of beryl, valued for vivid to deeply saturated green color.
Color
Emerald may range from lighter vivid greens to richer and more saturated tones.
Durability
Emerald measures around 7.5–8 on the Mohs scale and generally benefits from more careful handling.
Clarity
Internal features can influence clarity and contribute to emerald's individual character.
03
Ruby
Ruby is the red variety of corundum — the same mineral family as sapphire. Its defining character comes from color, ranging from brighter vivid reds to deeper saturated tones.
What Is It?
Ruby is red corundum, distinguished by the coloration responsible for its red appearance.
Color
Ruby varies from brighter vivid red to richer and deeper red tones.
Durability
Ruby reaches 9 on the Mohs hardness scale and is highly suited to regular wear.
Lab-Grown
Lab-grown ruby shares the essential mineral composition of natural ruby while having a different origin.
04
Alexandrite
Alexandrite is a variety of chrysoberyl known for its remarkable color-change effect. Its appearance can shift as the surrounding light changes, giving the gemstone a distinctly dynamic character.
What Is It?
Alexandrite is a color-changing variety of the mineral chrysoberyl.
Color Change
Its appearance shifts as different wavelengths dominate the surrounding light.
Durability
Alexandrite measures approximately 8.5 on the Mohs hardness scale.
Lab-Grown
Lab-grown alexandrite is created through a controlled gemstone growth process.
At a Glance
Compare the Gemstones
Compare color, mineral family and durability to understand how each gemstone brings a different character to jewelry.
Emerald
- Mineral
- Beryl
- Known For
- Distinctive green
- Mohs Hardness
- 7.5–8
- Regular Wear
- More careful handling
Ruby
- Mineral
- Corundum
- Known For
- Rich red color
- Mohs Hardness
- 9
- Regular Wear
- Excellent
Alexandrite
- Mineral
- Chrysoberyl
- Known For
- Color change
- Mohs Hardness
- 8.5
- Regular Wear
- Very good
Gemstone Care
Care Essentials
Thoughtful everyday care helps protect both your gemstone and the setting around it.
- Clean gently with lukewarm water, mild soap and a soft brush.
- Avoid harsh chemicals and abrasive cleaning products.
- Remove jewelry before strenuous activity or situations where the setting may receive a hard impact.
- Store pieces separately to reduce rubbing against other jewelry.
- When not being worn, keep your piece in its original STDIAM walnut wood box.
Gemstone Guide
Frequently Asked Questions
Are lab-grown gemstones real gemstones?
Yes. Lab-grown sapphire, emerald, ruby and alexandrite are gemstone materials created in controlled environments. They share the essential mineral composition and crystal structure associated with their natural counterparts, while their origin and growth characteristics differ.
What is the difference between lab-grown and natural gemstones?
The primary difference is origin. Natural gemstones form through geological processes, while lab-grown gemstones are created under controlled conditions. Growth features, inclusions, availability and pricing can also differ.
Which gemstone is best suited to everyday wear?
Sapphire and ruby both reach 9 on the Mohs hardness scale and are particularly well suited to regular wear. Alexandrite is also highly durable at approximately 8.5. Emerald is hard but generally benefits from more careful handling.
How do I choose between sapphire, emerald, ruby and alexandrite?
Begin with the color and character that appeals to you most. Sapphire is known for rich blue, emerald for distinctive green, ruby for red and alexandrite for its changing appearance. Durability and how often you intend to wear the piece can also help guide your choice.
Do lab-grown gemstones fade over time?
Their inherent color does not normally fade through ordinary wear. Oils, lotions and surface residue may temporarily make a gemstone appear less vivid. Alexandrite naturally changes appearance under different light sources.
How should gemstone jewelry be cleaned?
For routine care, use lukewarm water, mild soap and a soft brush, then rinse carefully and dry with a soft, lint-free cloth. Avoid harsh chemicals and protect the gemstone and setting from hard impacts.
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