Is it jones or joness possessive ?

The possessive form of a noun depends on whether the noun is singular or plural, and whether it ends in “s” or not. In the case of “Jones”, which is a singular noun, the possessive form can be either “Jones'” or “Jones’s”.

The Chicago Manual of Style recommends using “Jones’s” as the possessive form for singular nouns ending in “s”, unless it would create an awkward or difficult-to-pronounce construction. In the case of “Jones”, “Jones’s” is the more commonly used form, and it is also the form used by many authoritative sources, including the Oxford English Dictionary.