You will need:
1. You are doing 2 separate calculations, so record your results for ring experiment 1 and 2 separately.
2. Weigh both rings.. write each mass down next to the letter A in each separate calculation.
3. Weigh the full glasses of water (it should be about to spill)
... write each mass down next to the letter B in each calculation.
4. Tie the cotton thread around each ring and slowly dip the ring into the water.
5. Let the water spill over the glass.
6. Take the ring out of the water. Re-weigh the glass... write the mass down next to the letter C.
7. For each experiment perform the calculation .... (B - C) / A = Specific gravity of the ring.
8. Are there any sources of error?
Eg. It's easier to measure greater volumes of displaced water. Why not try comparing iron vs rock?
9. If the 'cheap' ring is real gold, it's specific gravity should be the same as for the real gold ring. Of course, this experiment would be much easier to measure with a larger gold piece!