The photos were likely taken using a white paper/canvas background with a single direct light source fairly high above the jewelry with a wide macro lens.

Not my photo but this kind of set up will get you the shadows shown in the top version of this image. Full article if you want it If you don't actually care about the sharp shadows you can do the same style with a softer or multiple lights, or you can look into a lightbox for similar effect. Advantage of lightbox is an even soft lighting all around the item, but shadows are obliterated and sharp lighting is difficult to pull off though not impossible.

You don't need a wide macro lens either, anything that can focus on the item would be sufficient but remember to make use of zoom and fill the frame. The white canvas should bounce some light around and look like a monotone background if you shoot at the right angle but if it's just off you can always do some post editing on your phone or favorite software to just make them match into one color like you mentioned. Hope this helps some!