For a necklace, this is a pearl necklace, I suggest making a light light line to guide you to where u want the necklace because you want the necklace circular.

Now once u have made each pearl, it's time for shading. Shade pearls similar to each other. Also shade under the necklace at this point.

Now make the outline more definite under the necklace, don't do this above or it won't give the pearl effect.

Now shade on the top slightly and where the pearls shade against the neck.

Ta da!!! A pearl necklace, this is a student's starter from this guide, she is 9.

Now for a metal and diamond ring. I chose the ring for the materials. You can use these rules for all jewelry. So draw the basic outline of the ring, I started it from the center.

Now add the diamonds in the center. These are rectangular cut so make a small box in the center of each bigger box and connect the corners as if u were making a 3D rectangle.

Now make boxes for the other diamonds.

Now make circles in each box for the actual gems.

Now it's hard to see but make small strikes in a circular pattern around each diamond to give it a cut and sparkle effect.

Like this, so it looks like a kiwi cut in half.

Now shade the metal, go along with the shading on the picture or real jewelry. Add in the shape lines so it looks 3D and add the shading at the bottom and add a bit of shading in the rectangular gems.