The outer portion (1.5mm to 5mm) of the cerebrum is covered by a thin layer of gray tissue called the cerebral cortex. 1  The cerebral cortex is in turn divided into four lobes: frontal lobes, parietal lobes, temporal lobes, and occipital lobes. The cerebrum or telencephalon, along with the diencephalon comprise the two major divisions of prosencephalon (forebrain).
Gemstones from Africa. The traditional sources for colored gemstones are in Asia and South America, especially Burma, Sri Lanka and Brazil. However, these days Africa is generating most of the the excitement in the gemstone world.Looking at our own inventory of over 35,000 gems, about 50% of them originate from Africa.owever, these days Africa is generating most of the the excitement in the gemstone world. Looking at our own inventory of over 35,000 gems, about 50% of them originate from Africa.
Beside yellow and blue, topaz also occurs as orange stones. These orange gemstones come from two varieties of topaz, namely, precious topaz and imperial topaz, which is a pinkish orange and the more valuable of the two.Topaz is the traditional and modern birthstone for November.ext to red and purple diamonds, the orange precious stone is the rarest of diamonds. Like the rest of its kind, this orange rock is the hardest of minerals, and endowed with a high refractive index that makes this orange jewel shine brilliantly. For this reason, diamond is the most expensive of orange gemstones.