>>4848These jade statues are tough choices for reference, because the material has a smooth surface, requiring a lot of gradients, while they also have these fine ink shadings, influencing tones and perception of shape.
I would recommend to use different materials, like charcoal or pencil for the actual statue and ink or a fine pen for the details, as if you would carve the object out of the blank sheet and then paint it, just like the original artist. This way you can reduce the thickness of your outlines, setting the darkest tones with shading and clean up the borders of strong contrast. This will make the object almost pop out of the picture.
Another thing I want to advice is the colorization of the background. In drawings it's just normal for the object to end up darker than the reference, as you continue to add shading. With a very dark background however you can enhance the foreground without removing anything well-done. Again charcoal or a soft pencil like 4B and up is ideal for that. Ink and pen can be used, but can even be too dark for the object in the foreground, creating an unsettling impression of undertow.
>>4911With charcoal better double the size of your picture and avoid smudging for gradients unless you are really experienced or choose to use it like paint and smudge the whole picture. See these bright dots in the center? They remain in every part when you draw with charcoal on paper or canvas, but disappear in the areas you smudged. One can utilize this to create blurry backgrounds or contrasts of roughness for example, but otherwise it distorts the impression of the surface on a single object.