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.
Aquamarine is a blue to green-blue variety of precious beryl. The beryl group of minerals is most famous for chromium-rich, green emerald, which happens to be one of the 'precious four' gems of the world (diamond, sapphire and ruby are the remaining three).quamarine and emerald belong to the same family, but they are surprisingly different. Aquamarine and emerald are both beryllium aluminum silicates. While emerald is colored by trace amounts of chromium (and vanadium), aquamarine color is the result of iron impurities within colorless beryl crystal.