Highly valued as gemstones, emeralds are a grass-green variety of beryl. The capacity of emeralds to deflect light and to break white light into its component colors is not high, so cut stones display little brilliancy or fire (flashes of color). The color that gives this gem its value comes from the presence of small amounts of chromium. The most important production of fine-quality gem material is Colombia; emeralds are also mined in Russia, Australia, South Africa, and Zimbabwe. Synthetic emeralds are identical to natural crystals and may rival them in color and beauty.
1 One of the primary reasons why BMI is a flawed measurement tool is that it uses weight as a measure of risk, when it is actually a high percentage of body fat that makes a person obese.  Many experts are now leaning toward body fat percentage as the most accurate measure of obesity.
The graphic that shows why BMI is useless: Scientists reveal how radically different body shapes can have the SAME readings. Most of us step on the scales to check how much we've indulged ourselves over the holidays.