1. Main Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it.

2. Top left Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Quartz Quartz is a crystal form of silicon dioxide (Si0 2 ), and grows in a 6-sided prism ending in a 6-sided pyramid. Smoky quartz The colour of smoky quartz is thought to come from either iron impurities, titanium impurities or irradiation. It’s relatively common.

3. Top mid Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Quartz Quartz is a crystal form of silicon dioxide (Si0 2 ), and grows in a 6-sided prism ending in a 6-sided pyramid. Citrine The colour of citrine is thought to come from iron impurities or irradiation. Relatively rare in its natural form, it’s more common for a citrine to actually be a heat- treated amethyst.

4. Top right Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Quartz Quartz is a crystal form of silicon dioxide (Si0 2 ), and grows in a 6-sided prism ending in a 6-sided pyramid. Amethyst The colour of amethyst is thought to come from iron impurities or irradiation. This deep violet colour is quite rare.

5. Center left Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Garnet Garnets are a group of minerals varying in the general formula X 3 Y 2 (SiO 4 ) 3. The crystal structure is usually dodecahedral (12- faced) although it can also be cubic (6- faced). Pyrope (“Red Garnet”) Pyrope is a magnesium-aluminium silicate - Mg 3 Al 2 (SiO 4 ) 3. It is formed in high-pressure rocks.

6. Center mid Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Garnet Garnets are a group of minerals varying in the general formula X 3 Y 2 (SiO 4 ) 3. The crystal structure is usually dodecahedral (12- faced) although it can also be cubic (6- faced). Rhodolite Rhodolite is a variety of Pyrope with a “rosy” colour. It can easily be mistaken for the more valuable Pink Tourmaline.

7. Center right Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Garnet Garnets are a group of minerals varying in the general formula X 3 Y 2 (SiO 4 ) 3. The crystal structure is usually dodecahedral (12- faced) although it can also be cubic (6- faced). Spessartite Spessartite is a manganese aluminium garnet - Mn 3 Al 2 (SiO 4 ) 3. It was first found in Spessart, Germany. There are only a few places in the world where this gem occurs.

8. Bottom left Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Tourmaline The group of minerals called tourmalines some of the most chemically complicated silicates. The constituent elements vary to give a wide variety of colours. Blue-green As with many types of tourmaline, blue- green tourmaline is dichroic – depending on the viewing angle, it appears either blue or green. The colour is thought to be due to traces of chromium and copper.

9. Bottom mid Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Tourmaline The group of minerals called tourmalines some of the most chemically complicated silicates. The constituent elements vary to give a wide variety of colours. Yellow The colour of yellow tourmaline is thought to be due to traces of magnesium. It is found in Malawi and Zambia.

10. Bottom right Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Tourmaline The group of minerals called tourmalines some of the most chemically complicated silicates. The constituent elements vary to give a wide variety of colours. Pink Pink tourmaline is a variety of Rubellite (deep red) which in turn is a variety of Elbaite - Na(Li 1.5,Al 1.5 )Al 6 Si 6 O 18 (BO 3 ) 3 (OH) 4.