2. INTRODUCTION Some types of gemstones are diamonds (they are the hardest material that we know of), ruby, sapphire, emerald, aquamarine… Their structure is geometrical, for example the diamond has a cubic system, the ruby and the sapphire have a rhombohedral system, and the emerald has a hexagonal system.

3. THE AQUAMARINE The aquamarine is a mineral that comes from beryl, it’s a very precious gemstone and it is the colour of the sea. It has a hexagonal system

4. The king Luis VI wants a crown with nine gemstones. He knows that one of them (only one) is fake. And he also knows that all the real gemstones have the same weight, except the false one, which is heavier than the others. With a balance, the king tried to find the fake gemstone only using the balance twice. WAS IT POSSIBLE ? GEMSTONES

5. THE END