For this sketch I used a plain tiered cake as the base, then added a jeweled border to each tier. I changed the color of the alternating tiers by making a copy of the plain tier and coloring them blue, then adjusting the opacity. I used a photo of a strand of pearls and the transform/ warp tool to place them on the tiers.
If you were going to make this cake from edible materials, I'd use fondant or gumpaste in a mold for the border, then paint it silver. The pearls would be easy to make in fondant but would take a loooong time to place on the cake, so if you're going to do something like this you should plan for a lot of decorating time, or make the pearls in a strand and drape them on the cake.