Top 10 Gemstones with a Hexagonal Crystal System

The hexagonal system gives the crystals six sides. Three of these are equal in length and meet at 60° to each other. The C, or vertical axis, is at 90° to the shorter axes.

Mineralogists sometimes divide the hexagonal crystal system into two systems based on their external appearance - the hexagonal and the trigonal. But the trigonal crystal system is a subsystem of the hexagonal and most gem references will list the trigonal system as hexagonal.
The Top Ten
1 Taaffeite

There were images to these items... Why they suddenly disappeared?

Clearly a Hexagonal Crystal Subsystem. It's visible

2 Beryl

Hexagonal subsystem, obviously. It's also visible.
The image shows Red Beryl, which is the rarest color for beryl, but beryl is usually colorless

3 Ruby

Its crystals have a Trigonal shape, so it's Trigonal subsystem of the Hexagonal system

4 Aquamarine

It belongs to the Hexagonal subsystem because aquamarine is just blue beryl and all beryls are with Hexagonal shapes

5 Sapphire

Trigonal subsystem (the image shows black Sapphire but they can occur in all colors except red)

6 Emerald

Hexagonal subsystem - because Emerald is actually deep green beryl

7 Benitoite

Hexagonal subsystem.
Its blue color is awesome (color isn't related to the crystal system though)

8 Tourmaline

Trigonal subsystem (the image shows Green Tourmaline - green is the classic color of the gem, but they can be different colors)

9 Morganite

Hexagonal subsystem because it's pink beryl

10 Amethyst

Trigonal subsystem (amethyst is a semi-precious variety of quartz )

The Contenders
11 Jeremejevite

One of the rarest gems in the world

12 Citrine
13 Poudretteite

Another extremely rare gem first found in Quebec, Canada

14 Musgravite
15 Sugilite
16 Hibonite
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