A monochromatic oil painting to study the values

An indirect painting to study the values. As you see in the different stages of this still life painting I have tried to do it in two layers. First stage being creating a rough sketch with burnt sienna and second stage covering it with different shades of blacks and whites. I m thinking of doing one more layer to make it colorful. :) Canvas size: 16" x 20"
colors used: lamp black, titanium white and burnt sienna