I don't suggest it, but you could buy a Macro lens! You'll find plenty of lens buying advice online. I would start at your camera manufacturer's website and look for free Macro tutorials and training before buying a new lens.

Want a cheaper alternative before you buy a pricey and specialized Macro lens? Read on...

Instead of a Macro lens, learn the proper technique for photographing small objects. Then, set up a suitable work surface, take control of your lighting, and stabilize your camera which will be in auto-focus mode.

Should you use your camera's manual focus mode? It may be a lot of trouble for beginners. Instead use the brightest lighting your gem can tolerate without excess reflections and set the camera's most basic automatic mode. Focus should fall into place if you set your camera on a tripod and take lots of test shots. If you are not happy, then investigate your camera's manual focus settings.

If it were me, I would skip a Macro lens and start with the included (or kit) lens. And I would simply use the Automatic mode of my camera, with no special training needed, except trial and error. (If your camera has a dedicated Macro mode, you may try it that way as well as the simple Automatic mode.) No additional money or equipment is needed! Yes, with a Macro lens you might be able to move your camera a little closer, or your Macro might capture a bigger image size in each shot. But since your gem is not a moving object, who cares if your camera is 2 feet away or 2 inches away if you still get a good shot? And if your final image size seems too small, just use your image editing program to crop and magnify it.

Also, since your gems are not subjects that move, you can control both the lighting and the background. Skip the camera flash, which is a lot of guesswork for beginners. Instead choose a "continuous illumination source" like daylight or a desk lamp. Start inside during the daylight hours on a table near a window with a northern view. This avoids the direct rays of sunlight, which can be harsh illumination. If needed, set up desk lamp, or even a couple small LED flashlights resting on paperback books. See various online tutorials for lighting (and white balance) if you don't get the effect or the color you want.

With gems, or any mirror like object, reflections can be tricky. Reposition lighting until you get the effect you prefer. Also, gems will tend to pick up the color of nearby surfaces. Some people suggest shooting on black felt with a black drape in the background. Again, check for online tutorials.

Handholding your camera will probably give you many blurry shots. To add steadiness to your camera, I would definitely recommend a small tripod (or even a stack of books, etc.) to prevent your camera from moving as you take the shot. Try to use the self-timer (10 second countdown) to take the photo, and your nervous hands will not be wiggling the camera and blurring the image.