By the foregoing examples, it will be seen that the weight is multiplied by itself, and the product by the price per carat, which may be some other sum, according to the general characteristics of the stone. 5. This rule, however, is not extended to diamonds of more than 20 carats in weight; nor is this or any other rule of estimate strictly adhered to in every case; nevertheless, it probably comes pretty near to general usage. In the same country, a perfect ruby of 3-1/2 carats is worth more than a diamond of equal weight. A ruby weighing one carat may be worth 10 guineas; two carats, 40 guineas; three carats, 150 guineas; six carats 1000 guineas. A ruby of a deep red color, exceeding 20 carats, is called a carbuncle; and of these, 108, weighing from 100 to 200 carats each, are said to have been in the throne of the Great Mogul. 6. Some of the European sovereigns have, in their possession, diamonds of great value, several of which were originally brought to England from India. The _Pitt_ or _Regent diamond_ was purchased in India by Robert Pitt, grandfather of the Right Honorable William Pitt, for £12,500 sterling. It was brought to England in a rough state, and £5000 were there expended in cutting it; but the cuttings themselves were worth £7000 or £8000. It was sold to the Duke of Orleans, for the King of France, at the enormous price of £136,000. Its weight is 136 carats; and, before it was cut, it was as large as a common pullet's egg. 7. A celebrated diamond, in the possession of the emperor of Russia, is denominated the _Effingham_ or _Russian diamond_. It was brought to England by the Earl of Effingham, while governor-general of India, and sold to the Empress Catharine for £90,000. It is inferior in shape to the last mentioned, but superior to it in magnitude, it weighing 198 carats. The Queen of England has a diamond which cost £22,000. 8. The largest diamond hitherto known was found in the island of Borneo, and it is now in the possession of the Rajah of Mattan. Many years ago, the governor of Batavia offered, in exchange for it, $150,000, and two large brigs of war with their equipments and outfit; but the rajah refused to part with the jewel, to which the Malays supposed miraculous power belonged, and which they believed to be connected with the fate of his family. The weight of this diamond is 367 carats. 9. Other jewels, belonging to different sovereigns, as well as to private persons, might be mentioned; but a sufficient number has been noticed to enable the reader to form some idea of the extravagant expenditures often made for articles of imaginary value. We will merely add that the royal family of Portugal is in possession of a stone which was formerly supposed to be a diamond, but which has lately proved to be some kind of crystal of little value. The weight of this stone is 1680 carats; and, until its real character was discovered, it was valued at 224 millions sterling.