Lightly included stones usually go safely into ultrasonic cleaners. When buying, use a few simple guidelines. Size, quality, color and price are absolutely related. You can get a ruby twice the size for the same price if you are willing to have one with less than half the color and quality. When one feature improves, others have to come down to hold the same price.
Shape is a personal preference.
Most rubies are fashioned as ovals or cushion-cuts. But there are emerald-cuts, rounds and more if those set your heart pumping. Cutting standards are far more relaxed for colored stones than for diamonds. Dealers here often have to recut off-center and asymmetrical gems. Clarity guidelines are not as rigorous with rubies as with diamonds because a natural flawless ruby is a virtual impossibility.