Q 01/05

The Mohs hardness scale used for gemstones was introduced in 1812 by a mineralogist of which nationality?

A) Swedish

B) British

C) French

D) German

Answer · why

D) German

Friedrich Mohs ranked ten reference minerals by which could scratch which, and the scale is still the standard shorthand for gem durability.

Q 02/05

Which mineral sits at 1, the softest point, on the Mohs scale?

A) Gypsum

B) Calcite

C) Talc

D) Fluorite

Answer · why

C) Talc

It can be scratched with a fingernail; gypsum is 2, calcite 3 and fluorite 4 on the same scale.

Q 03/05

Rubies get their red colour from traces of which element?

A) Iron

B) Titanium

C) Chromium

D) Vanadium

Answer · why

C) Chromium

The same aluminium-oxide mineral with different trace metals gives every other colour of the gem family, including the rare pink-orange padparadscha.

Q 04/05

Which gemstone is the modern birthstone for September?

A) Peridot

B) Sapphire

C) Opal

D) Topaz

Answer · why

B) Sapphire

Peridot belongs to August, opal to October and topaz to November on the same list.

Q 05/05

How many carats does the Hope Diamond weigh?

A) 45.52

B) 59.60

C) 68.00

D) 105.6

Answer · why

A) 45.52

Under ultraviolet light the stone glows with an eerie red phosphorescence, one of the traits used to identify it.