They are the diamond, sapphire and ruby, and the Emerald.
The latter is one of the most famous of the Beryl group of minerals, another famous gem is Aquamarine, also from the Beryl group of minerals, famous for March born babies of course. But Aquamarine is liked by many because of its beautiful breathtaking sea-blue colors which can range from light to dark-blue. It vibrates well with the soulful nature, Mystical and clear, it brings any metal to life, be it white gold, yellow gold or rose gold. Aquamarine is exceptionally hard and has an outstanding vitreous (glass-like) luster.
Aquamarine and emerald are beryllium aluminum silicates. Emerald is colored by trace amounts of chromium (and vanadium), aquamarine gets its color from iron impurities within colorless beryl crystal. Unlike the emerald, aquamarine has excellent transparency and clarity. Like seawater, aquamarine can be light-blue, dark-blue, blue-green and green-blue. The dark, deeply saturated blue is the most desirable and valuable aquamarine color. The intensity of color and the clarity of the stone are the most important criteria when evaluating aquamarine, followed closely by quality of cut. On the Mohs scale aquamarine is 7.5 - 8.
It was in 1910 when the "Minas Gerais" mine in Marambaya, Brazil, unearthed a stone of 243 lb (110.5 kg), 18 inches (48.5 cm) long and 15.5 inches in diameter, the largest find of gemstone quality aquamarine that was cut into many gemstones with a total weight of more than 100,000 carats.
The 'Dom Pedro', weighing 26 kg and cut in Idar-Oberstein, Germany in 1992 by the gemstone designer Bernd Munsteiner, is the largest single piece of aquamarine to have ever been cut.