Light, locked in stone.
A working codex of the gem kingdom. Real gemological data for seventy-two stones. The Mohs scale you can scratch through. Seven ways atoms stack into crystals. And every optical trick that makes a gem worth chasing.
Every stone carries its true mineral species, chemical formula, crystal system, Mohs hardness, refractive index, and specific gravity. The numbers a gemologist would actually quote.
Refraction, dispersion, asterism, opalescence, and color change get their own demos. See why a star sapphire holds a moving star and why diamond throws fire.
The seven crystal systems are the grammar of mineralogy. Learn how cubic, hexagonal, and triclinic lattices decide a gem's symmetry, cleavage, and optical behavior.
The Hope Diamond's curse, the Black Prince's Ruby that is not a ruby, and the Cullinan that became the crown jewels. Lore, localities, and care notes on every stone.
The Collection
Seventy-two gemstones, each a real mineral with real numbers. Filter by color family or hardness, search by name, then open any stone for its full gemological dossier.
The Mohs Hardness Scale
Friedrich Mohs ranked ten reference minerals in 1812, each able to scratch the one below it. The scale is ordinal, not linear: diamond is roughly four times harder than corundum, though they sit one step apart. Click any step.
The Seven Crystal Systems
Every crystalline gem belongs to one of seven lattice geometries, defined by their axes and the angles between them. The system governs symmetry, cleavage, and how a stone bends light.
The Gem Spectrum
Color in gems comes from trace elements, structural defects, and the way a lattice absorbs light. Hover a band to see which stones live there, then jump straight to any of them.
Hover a color band
Each band lists the gemstones whose dominant body color falls in that range, and what causes it.
Optical Phenomena
Beyond plain color, certain stones do things with light that border on the supernatural. Stars that follow you across the room. Internal flame. Color that flips from daylight to candlelight.
The Birthstone Calendar
The modern list was standardized by the American National Retail Jewelers Association in 1912 and updated since. Tap a month to open its primary stone.
Anniversaries & Zodiac
Beyond the gemology, gems carry centuries of custom. These anniversary and astrological pairings are traditional associations, not science, but they are part of why we give stones meaning. Tap any to open its dossier.
Wedding Anniversary Gems
Zodiac Stones
Legendary Gemstones
A handful of stones are famous enough to have their own biographies. Cursed diamonds, record sapphires, and the largest rough ever pulled from the earth.
The Physics of Color
Color in a gem is not one thing. It can come from an essential element, a trace impurity, electrons leaping between atoms, structural defects, or pure geometry with no pigment at all. Here are the seven mechanisms.
Cuts & Shapes
A rough crystal is just potential. The cutter decides how much light comes back out. From the mathematically perfect round brilliant to the antique rose cut, every shape is a different bargain between brilliance, weight, and beauty.
The Mineral Families
Most famous gems are siblings. Ruby and sapphire are one mineral. Emerald, aquamarine, and morganite are another. Understanding the families is the fastest way to make sense of the whole kingdom.
Property Comparison
Rank the collection by the measurements that matter. Hardness predicts durability, refractive index and dispersion predict sparkle and fire, and specific gravity helps tell look-alikes apart. Click any bar to open the stone.
Treatments & Enhancements
Almost every gem on the market has been improved somehow. Most treatments are accepted and stable, a few are fragile, and all of them should be disclosed. Knowing the difference protects your money.
The Inclusion Atlas
Inclusions are not always flaws. They are a gem's fingerprint, telling a trained eye whether a stone is natural or synthetic, treated or untouched, and often exactly where on Earth it formed.
World Localities
Geography is destiny in the gem world. A handful of legendary deposits have set the quality standard for their species, and a documented origin can multiply a fine stone's value.
A History of Gems
From the turquoise mines of the pharaohs to lab-grown diamonds, the human relationship with gemstones is one of the oldest stories we have. A few of its turning points.
Synthetic & Lab-Grown
A synthetic gem is not a fake. It has the same chemistry and structure as the natural stone, grown in a lab instead of the earth. These are the methods that make them, and the clues that reveal them.
The Four Cs, and Beyond
Color, clarity, cut, and carat are the classic four. For fine colored stones, origin and treatment have become the modern fifth and sixth. Here is what each one really means.
The Care Matrix
The single most useful skill in owning gems is knowing what not to do. Match the cleaning method to the stone, and a collection lasts for generations.
The Glossary
The working vocabulary of the trade, from adamantine luster to zoning. Jump by letter or scan the full list.
The Gemologist's Quiz
Ten questions on hardness, chemistry, color, and lore. No looking at the cards.
Field Notes
The questions every beginner asks, answered without the jewelry-counter spin.
The kingdom is open.
Seventy-two stones are waiting in the vault. Find your birthstone, settle the hardest-gem argument, and learn why an opal looks like it has a galaxy trapped inside.
Return to the collection