Most jewelry work is done with propane or natural gas. Some still use acetylene, but for the cleanest fuel gas choice, hydrogen is used. Normally, the regulator you use for acetylene will work for hydrogen. Keep in mind that a tip which produces a very small flame, at a neutral setting, has the same temperature as a very large tip, at neutral setting. The difference is in the heat energy produced, or BTU's.
Technique is also a factor.
Acetylene delivers maximum BTU's close to the tip. Alternate fuels, such as propane and natural gas, deliver heat energy farther out in the flame. Consequently, you need to hold the tip farther away from the surface or material to be heated. The Little Torch will work with any fuel gas choice. Natural gas is popluar, but, sometimes the pressure is limited.