Amber is fossil tree resin, which is appreciated for its color and beauty. Good quality amber is used for the manufacture of ornamental objects and jewelry. Although not mineralized, it is often classified as a gemstone.
A common misconception is that amber is made of tree sap; it is not. Sap is the fluid that circulates through a plant's vascular system, while resin is the semi-solid amorphous organic substance secreted in pockets and canals through epithelial cells of the plant.
Because it used to be soft and sticky tree resin, amber can sometimes contain insects and even small vertebrates.
Semi-fossilized resin or sub-fossil amber is known as copal.
Amber occurs in a range of different colors. As well as the usual yellow-orange-brown that is associated with the color "amber", amber itself can range from a whitish color through a pale lemon yellow, to brown and almost black. Other more uncommon colors include red amber (sometimes known as "cherry amber"), green amber, and even blue amber, which is rare and highly sought after.
A lot of the most highly-prized amber is transparent, but cloudy amber and opaque amber is also very common. Opaque amber contains numerous minute bubbles. This kind of amber is known as "bastard amber", even though it is in fact true amber.

Carnelian is one of the birthstones listed in the ancient Arabic, Hebrew, Italian and Roman tables and is a Zodiac birthstone for the signs of Leo and Virgo.
Carnelian is a form of chalcedony, a member of the quartz family and most Carnelian is heat treated today to enhance the reddish brown color.
Folklore suggests that carnelian was used protect the traveler after death and guard against evil. Carnelian's healing properties are thought to help purify the blood, relieve menstrual cramps and back pain. It is also thought to be beneficial in the treatment of infertility and is worn to enhance passion and desire.

Citrine is a variety of quartz. It ranges in color from a pale yellow to brown. Citrine has ferric impurities, and is rarely found naturally. Most commercial citrine is in fact artificially heated amethyst or smoky quartz. Brazil is the leading producer of citrine, with much of its production coming from the state of Rio Grande do Sul.
Citrine

Citrine is one of three traditional birthstones for the month of November.

It is nearly impossible to tell cut citrine from yellow topaz visibly.