The density of the substance is 10.5 g/cm³.
The jewelry is made out of Silver.
Density ρ is defined as the ratio of mass m of the substance to its volume V. The cylinder contains a volume V₁ of water and when the jewelry is immersed in it, the total volume of water and the jewelry is found to be V₂.
The volume V of the jewelry is given by,

Substitute 48.6 ml for V₁ and 61.2 ml for V₂.

calculate the density ρ of the jewelry using the expression,

Substitute 132.6 g for m and 12.6 ml for V.

Since
,
The density of the jewelry is 10.5 g/cm³.
From standard tables, it can be seen that the substance used to make the jewelry is silver, which has a density 10.5 g/cm³.