It is sometimes oiled to hide the internal flaws. The best blue, Aquamarine, comes from Brazil today, and can be found in very large, and very clean crystals. The color is caused by iron impurities, and it can be heat treated to enhance the color. It is more expensive than blue topaz, but far less expensive than emerald.
Asterism is possible in aqua producing either cats-eye or even star stones.
The red color is due to manganese, and the best material comes from Utah. Yellow to yellow-orange samples are referred to as golden beryl. True Heliodor is valued by collectors but not seen much in jewelry, the golden beryls are seen often in jewelry but are not as expensive as aquamarine. It contains cesium and lithium, but the color agent is a trace of manganese. Is not used extensively in jewelry and is not expensive.