A period is a bleed from the womb (uterus) that is released through the vagina. It happens approximately every 28 days, although anywhere between 24 and 35 days is common. Periods can begin when girls are between 8 and 16 years old, but usually start around the age of 12.
Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5â8 on the Mohs scale. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor.
Natural, transparent Emerald is one of four âpreciousâ gemstones (including Diamond, Ruby and Sapphire), and is the green variety of Beryl, a beryllium aluminum silicate mineral colored by trace amounts of chromium and/or vanadium.