Question 790435
Essentially, all you need to use is a unit converter, but thanks to us tutors, should you not need the hassle.

--

A mass of 1.03g is the equivalent of 1030mg, so you ultimately need to rid the decimal and add a zero.

1030 - 976 = 54, so their difference is 54mg.

Thus, the larger diamond is 54mg heavier than the smaller.