I'm trying to practice using the array modifier by creating a ring and having a series of gems that wrap around the surface. I created an empty in the centre of the ring that would serve as a pivot point, but when I clicked object offset (which I assume is the correct thing to do?) it created copies that became progressively more massive. What have I done incorrectly?
Your object and your empty have different scale values. Hover over your object's scale values and press CTRLC, then select the empty, hover over its X scale value and hit CTRLV. Repeat for Y and Z (provided your object is uniformly scaled).
Alternatively: Select your empty, then shift-select your object, rightclick on the scale values and say: copy to selected.
Any differences of rotation, location or scale between the two objects get multiplied for each new copy. That can be pretty powerful.
Two array modifiers on top of each other. The empties just differ a bit in scale, rotation and location.