This morning I took some ground decaf coffee (from the previous day), and put it under the microscope. Lit from below (the default for brightfieqld microscopes), it looked pretty boring, just a silhouette.
Coffee grounds silhoetted by the microscope light
But when I turned down and later off the microscope light and used a simple (but fairly bright at 385 lumens) hand-held flashlight to light the coffee, color and texture popped out.
Coffee grounds lit a little from below with the microscope light & above with a flashlight
Coffee grounds lit with just a flashlight