An assembly for holding or supporting a timepiece balance spring, including a balance spring stud and a stud-holder, wherein the stud-holder includes a base having at least one circular portion, the base including, on the circular portion, a first lug and a second lug each extending radially; one of the two lugs including an elastic arm extending from the lug, in a direction parallel to that of the base, towards the other lug, the elastic arm forming with the base a housing for housing the balance spring stud therein and in that the first and second lugs are able to cooperate with a tool to allow the balance spring stud to exert a stress on the elastic arm to deform the latter and permit the assembly or disassembly of the stud.