Ali baba and the ashrafis
Most of us have heard the famous tale of Ali baba from the Arabian Nights. Ali baba was a poor man who lived by selling firewood. Once he overheard some robbers who was going to hide their looted treasure in a secret cave. Ali baba sneaks into the cave, and sees heaps of gold and silver and other treasures, but he wisely take nothing but "ashrafis":
"When he stood within the cave, its door had closed upon him, yet he was not dismayed, since he had kept in memory the magical words, and he took no heed of the precious stuffs around him, but applied himself only and wholly to the sacks of ashrafis."
(translated by Sir Richard Burton, 1850)
So what are the ashrafi's? They are gold dinars, weighting 3.38 grams, their diameter was 16.8 mm. They are named after Sultan Ashraf Barsbay of the Mamluk dinasty, who ruled Egypt for nearly 150 years. They are also called "Circassian" Mamlukes because the group originated in the Caucuses.

I don't quite understand Ali baba's enthusiams for the ashrafi dinar, since it seems that Sultan Ashraf Barsbay actually devaluated the dinar, which was made from pure gold. In 1425 AD, Sultan Ashraf issued a decree to stop using pure gold in money production, and he collected and re-mint the gold dinars with different weights, to match that of the Venetian ducat, the prevalent gold trade coin of the day. Until then the dinar had always been a gold coin of approximately 4.25 grams, modeled after the Byzantine solidus.
Modern islamist historians see a western influence in this change. And the islamic gold dinar, today's bullion gold coin of the islam world, produced by the Islamic Mint, weights 4.25 g just as the old dinar, before the ashrafis.
A note about the translator, Sir Richard Burton. He was an interesting figure with an adventurous life, look up his name in Wikipedia. He traveled a lot in the Arabian world, he got even to Mecca, disguised as an arabian merchant. He had some interest in coins, as it is evident from his book "First footsteps in East Africa". In this book he writes about his voyage to Harar, a small emirate in today's Ethiopia.
The only specie current in Harar is a diminutive brass piece called Mahallak - hand-worked and almost as artless a medium as a modern Italian coin. It bears on one side the words: Zaribat el Harar, the coinage of Harar. On the reverse is the date, A H. 1248. The Amir pitilessly punishes all those who pass in the city any other coin.
Lieut. Cruttenden remarks, "The Ashrafi stamped at the Harar mint is a coin peculiar to the place. It is of silver and the twenty-second part of a dollar. The only specimen I have been able to procure bore the date of 910 of the Hagira, with the name of the Amir on one side, and, on its reverse, 'La Ilaha ill 'Allah.' " This traveller adds in a note, "the value of the Ashrafi changes with each successive ruler. In the reign of Emir Abd el Shukoor, some 200 years ago, it was of gold." At present the Ashrafi, as I have said above, is a fictitious medium used in accounts.