Inferior quality of jewelry

In June 2013 we purchased a wedding set from Sterns on lay-buy which was then received in September 2013. In January 2014 a diamond fell out which was then repaired and replaced because the ring was still under warranty. A year later February 2015 another diamond fell out - It looks as if it could be the same diamond that fell out originally. Because it is past the 6 month warranty period i need to pay for the repairs. My problem is - this is the 2nd diamond to have fallen out in a space 1.5 years. So its either the ring is of absolute poor quality or if its the same diamond that previously fell out then the repairs were done ***********ly . It is enough the ring set was expensive but do i have to budget every year to replace a diamond if this is the case? I never thought that a wedding ring can be such an embarrassment to display due to STERNS poor standard of quality.<br>