what is the material???? there are many stones that will show a difference in color, you need to know the material. some mexican topaz can look colorless through the side but when cut may show color, a pinkish or brown when cut down the “c” axis, don’t forget to tip the table 5 degrees off the c axis, on any topaz. some amethyst has the color in the point of the crystal, the tip s/b the pavilion (bottom) of your stone. you want to choose the color showing direction for sure, just be aware of any hardness zones and cleavage plains. the color direction will be your crown and pavilion. gemmakermz@cs.com 509-783-9337
also keep in mind stones like tourmaline are bi colored one color through the side and darker color though the end of the crystals in most cases cut using side for top and bottom, if Very light and large enough to cut a stone through the end it will darken it.