This tutorial reinforces the lessons learned in the sphere tutorial, adding a slight warm and cool contrast. Use the photograph for your reference image.
Steps 1 and 2
1. Start with black and white paint and some oil medium. Draw the outline of the cone and its cast shadow with paint mixed with enough medium to make it runny and easy to move. Use a pointy brush, like a small round.
2. Paint a dark triangle with black for the deepest part of the shadow. Paint the cast shadow with dark gray and a darker proximity shadow (where the object would touch the surface it sits on.) Paint the light side of the cone white. (Mine is a little darker so you can see it, and I added a tiny bit of yellow for warmth.) On the far left of the cone add a tiny bit of blue to the mid-tone gray for a cool reflected light.
Steps 3 and 4
3. Paint a drop shadow in the background so that the foreground is lighter and it grades to a dark gray at the top of the canvas. Keep your individual color shapes on the cone separate. When you blend (Step 4) you want to keep them like they are. You are only blending the transition space, or where the shapes meet.
4. You want to blend everything while it's wet. Use strokes going in all directions. Don't over-blend or your contrast will disappear. You want your darks dark and your lights light and a smooth transition in between. It's important to smooth the meeting place where the object and background and shadow touch each other. The cast shadow can have a blurrier edge than the object, especially as it gets farther way from the sphere.