Crystal morphology, rendered precisely.
159 minerals with FGA-accurate crystallographic data, rendered live from open-source code. Study, practise, and reason about coloured gemstones: gallery, calculators, quiz, and timed exam included.
Free and open-source · Open access, no registration
cubic[m3m]:{{111} Built for the full FGA curriculum, and the developers who work with it.
A complete toolkit for FGA students, gemmologists, and crystal enthusiasts.
Crystal Gallery
Explore 159 mineral families and 216 crystal expressions with FGA-accurate data and interactive visualisations.
CDL Playground
Write Crystal Description Language code with live preview, syntax highlighting, and multi-format export.
Documentation
Complete API reference, CLI documentation, and CDL specification for developers.
Learn
FGA curriculum-aligned content covering crystal systems, optical properties, and identification.
Describe crystals with precision
CDL is a domain-specific language for defining crystal morphology. Combine Miller indices, point groups, and modifications to create accurate crystal representations.
cubic[m3m]:{111}@1.0 + {100}@1.3Truncated octahedron with cube faces
CDL Syntax Reference
system Crystal system (cubic, hexagonal, trigonal, etc.) [group] Point group symmetry (m3m, 6/mmm, etc.) {hkl} Miller indices defining crystal forms @dist Distance from origin (relative size) + Combine multiple crystal forms Seven Crystal Systems
Comprehensive coverage of all crystal systems with accurate symmetry operations.
Cubic
Diamond, Garnet, Spinel
Hexagonal
Beryl, Apatite
Trigonal
Quartz, Tourmaline, Corundum
Tetragonal
Zircon, Rutile
Orthorhombic
Topaz, Peridot, Tanzanite
Monoclinic
Gypsum, Orthoclase
Triclinic
Plagioclase, Kyanite
Test Your Knowledge
756 questions across 8 categories, generated from FGA curriculum content. Practise at your own pace or challenge yourself with timed exams.
Practise Mode
Learn as you go
- Immediate feedback after each question
- Detailed explanations and references
- "Learn more" links to study material
- No time pressure
Exam Mode
FGA-style assessment
- Timed sessions (30, 60, or 90 minutes)
- Flag questions for review
- Results breakdown by category
- Full question review after submission
Ready to visualise crystals?
Start with the interactive playground or explore our gallery of 159 mineral families.