I was synthing these today for bonecraft skill relativily cheap all the parts stack however, when i started i found i got a .1 goldsmithing skill, i am lvl 50 goldsmithing exactly, so the goldsmithing cap for this is not 50, however i have not been failing them at an a more then normal rate which makes me suspect it is close to 50 but not 50. i will get back to here when i stop skilling on gold
*edit* i have done more of these synths with 50 goldsmithing and confirmed it is not a lvl 50 cap i have done some searching and other sites report it as lvl 52 cap, this needs to be changed