Convert from stone to obolos [Ancient Greece]

Unit Definition (stone)
The stone is a traditional British unit of weight, rarely used in the U.S. Originally the stone varied in size, both from place to place and according to the nature of the item being weighed. A stone of sugar was traditionally 8 pounds, while a stone of wool could be as much as 24 pounds. Eventually the stone was standardized at 14 pounds avoirdupois or approximately 6.350 29 kilograms - a convenient size because it makes the stone equal to exactly 1/2 quarter or 1/8 hundredweight. Today the stone is used mostly for stating the weight of persons or animals.

Unit Definition (obolos [Ancient Greece])
The obolos [Ancient Greece] is a historic unit of weight or mass. The obol is a very small weight that originated as the weight of a tiny Greek coin. In ancient Greece the obolos was equal to 1/6 drachma, or roughly half a gram (8 grains).