What Are Gems?

What Are Gems? — page 1 — GLITTERY GEMS People around the world have loved gems for thousands of years We prize them for their beautiful colors and for their rarity The more difﬁcult it is to ﬁnd a gem the more valuable it usually is Some of the most valued gems are rubies emeralds sapphires and diamonds In the past most gemstones cost so much that only royalty could afford them Gemstones come in many different colors sizes shapes and cuts Sizes and shapes vary depending on how the gem will be used 4

What Are Gems? — page 2 — Today almost everyone can own gems of some kind Gifts of jewelry with gemstones are often given as a sign of affection For example diamonds are used in most engagement and wedding rings Some gems are thought to bring good health or good luck while others are said to be unlucky or even cursed Some famous gemstones are displayed in museums so that everyone can enjoy them The Crown Jewels of England are displayed in a museum inside the Tower of London In the past only wealthy people could afford to buy gems Do you think this made gems more appealing Why or why not Think About It 5

What Are Gems? — page 3 — HOW DO GEMS FORM Most gems are minerals which are natural substances found in the ground There are many minerals but only certain kinds are beautiful and strong enough to be gems Some gems are created by heat Deep under the surface of Earth a very hot substance called magma is always moving When magma pushes up between layers of rock it mixes with different minerals As the magma cools different types of gems can form Other gems are formed deep inside Earth The upper layers of Earth constantly press on the Obsidian forms from lava or magma that cools quickly Obsidian gems have been used for many purposes 6

What Are Gems? — page 4 — lower layers Where minerals are present this pressure along with heat from inside Earth creates gems Some gems form from evaporating water or water that is heated and turns to gas Water near Earth’s surface dissolves minerals it comes into contact with As that water evaporates gems can form and be left behind Compare and contrast the different ways gems are formed What do all gems have in common Compare and Contrast Turquoise is formed when water dissolves minerals in certain types of rock 7

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