Is this a lathe insert or a milling insert that you're asking about?
With the hole in the middle, it sounds like you might be referring to a SNMG 53x insert, where "x" is the operative for which radius is on the tip. There is no "standard:, though a SNMG 532 is probably more common. That would be a "2/64ths" (.03125) radius. An SNMG 533 would be .0473", a 531 would be .0156".
Does this help?