• Habit - the characteristic external shape commonly adopted by a crystalline material.  

  • Hallmark - a maker's mark or manufacturer's mark stamped or engraved on a piece of jewelry.

  • Hardness - the resistance to scratching.

  • Head - a prong setting used to hold a gemstone in place.  An example of this would be a solitaire diamond engagement ring.

  • Heat Treated Stones - gemstones which have their color improved or changed by means of the controlled application of heat.

  • Hematite - an iron oxide used both as a gemstone and in powdered form as a polishing abrasive.

  • Hue - the basic impression of a color.