If you don't have much to spend and don't mind manual focus, one macro I love and often recommend is the Tamron 52B 90mm f/2.5. It's a 1:2 macro lens, but can be brought down to 1:1 with extension tubes or Tamron's dedicated 2x teleconverter.
There are other manual focus macro options, most of which provide only 1:2 magnification. There's a Vivitar or Tokina 90mm I believe that gets down to 1:1 and then there's also the rather well-regarded Kiron-made 105mm f/2.8 macro that appears in a variety of names, which also gets down to 1:1. I have one with a Vivitar Series 1 label on it. Lester Dine is also another brand name you'll find it in.
As for mounting it to your EOS, the Tamron is an Adaptall-2 system lens, which is to say it takes a variety of interchangeable mounts. I believe there are EOS mounts available for Adaptall-2 lenses. With regards to the Kiron 100/2.8, this lens was available in a variety of dedicated mounts, most of which can be adapted to use with your EOS. Nikon, Pentax, Olympus mount lenses can be mounted to an EOS with an appropriate adapter, which can be found on
eBay for reasonable sums. Canon FD and Minolta MC/MD mounts
will not work on EOS cameras because infinity focus cannot be obtained. However, since you're doing macro work, you can buy mounts to use these lenses on EOS cameras that contain a corrective element so infinity focus can be attained, but these elements can also be removed from the adapter, which means you now have a lens that is good for close up work only. With a 100mm lens, this means that maximum distance from your camera will be about 6 feet. Which should be plenty for jewelry photography.