Gemstone Learning Center Blogs

Natural sapphire gemstones displaying blue, pink, yellow, purple, and other sapphire colors from the corundum mineral family.

What Is Sapphire? Colors, Formation & Gemstone ...

What Is Sapphire? What is sapphire? Sapphire is a gem variety of corundum, a crystalline aluminum oxide mineral with the chemical formula Al₂O₃. Although sapphire is most famous for its...

What Is Sapphire? Colors, Formation & Gemstone ...

What Is Sapphire? What is sapphire? Sapphire is a gem variety of corundum, a crystalline aluminum oxide mineral with the chemical formula Al₂O₃. Although sapphire is most famous for its...

Natural black obsidian and sheen obsidian showing glassy surfaces, internal structures, and natural variations used to identify genuine volcanic glass.

How to Tell if Obsidian Is Real: Natural vs. Fa...

How to Tell if Obsidian Is Real How to tell if obsidian is real can be surprisingly difficult because obsidian itself is a natural glass. Unlike identifying a crystalline gemstone...

How to Tell if Obsidian Is Real: Natural vs. Fa...

How to Tell if Obsidian Is Real How to tell if obsidian is real can be surprisingly difficult because obsidian itself is a natural glass. Unlike identifying a crystalline gemstone...

Natural black obsidian volcanic glass with a polished surface and characteristic dark glassy appearance.

What Is Obsidian? Formation, Types & Volcanic G...

What Is Obsidian? What is obsidian? Obsidian is a naturally occurring volcanic glass that forms when silica-rich molten rock cools so rapidly that crystals do not have enough time to...

What Is Obsidian? Formation, Types & Volcanic G...

What Is Obsidian? What is obsidian? Obsidian is a naturally occurring volcanic glass that forms when silica-rich molten rock cools so rapidly that crystals do not have enough time to...

Natural opal compared with synthetic and assembled opal examples showing play-of-color and different internal patterns.

How to Tell if Opal Is Real: Natural, Synthetic...

How to Tell if Opal Is Real How to tell if opal is real becomes especially important once you understand just how diverse this gemstone can be. Natural opal may...

How to Tell if Opal Is Real: Natural, Synthetic...

How to Tell if Opal Is Real How to tell if opal is real becomes especially important once you understand just how diverse this gemstone can be. Natural opal may...

Different types of natural opal including black opal, white opal, boulder opal, crystal opal, and orange fire opal.

Types of Opal: Black, White, Boulder, Crystal &...

Types of Opal: What Makes Each Variety Different? Types of opal can look so different that someone seeing them for the first time might assume they are completely different gemstones....

Types of Opal: Black, White, Boulder, Crystal &...

Types of Opal: What Makes Each Variety Different? Types of opal can look so different that someone seeing them for the first time might assume they are completely different gemstones....

Natural precious opal displaying multicolor play-of-color across the surface of the gemstone.

What Is Opal? Formation, Colors & Play-of-Color...

What Is Opal? What is opal? Opal is a hydrated form of silica known for an extraordinary optical phenomenon called play-of-color, where flashes of different colors appear to move across...

What Is Opal? Formation, Colors & Play-of-Color...

What Is Opal? What is opal? Opal is a hydrated form of silica known for an extraordinary optical phenomenon called play-of-color, where flashes of different colors appear to move across...