I have done something like this on Black Granite 12" tiles from Home Depot, and also on the beige Marble tiles. You change it to a grayscale, and adjust the brightness and contrast until the image stands out. It takes some experimenting, but I have got some great results. You might have to get rid of the background, to get it correctly done.There are some very good tips on the Sawmill Creek website, under the woodworking Laser section. Also, some great videos on YouTube.
On the black granite, I also did a negative image.
Watch Tutorial #3 here Tutorials – LightBurn Software It covers a lot on the topic of image engraving. You will probably not get much benefit from trying a DPI over 250.