Image post-reaction of cerium(III) oxalate

I am having issues with the imaging of crystals, cerium(III) oxalate, as the shape cannot be defined as it is a solid black crystal perhaps due to agglomeration. The SOP uses the 'top light' for these crystals. After, I have tried to use the 'bottom light' and it slightly provided a more transparent crystal image, but still no clear single crystals. I consistently used the 13mm3 spatula. Has anyone encountered this issue?