[SoothingDave]

No, the masses are given in grams (or kilograms), by definition. In a zero-G environment things weigh nothing, but their masses do not change.

And if the things are not being weighed at sea level, some one is getting ripped off. Maybe not perceptively, but in theory.

SD

[-YYZ-]

Only if you're using an uncalibrated force scale (spring scale, stress-meter based scale). A balance-type scale, like a triple-beam, doctor's scale or analytical scale (as used in chem labs) will read correctly in any gravitational field, or constantly accelerating frame of reference, within limits of course. Hmmm, how do you measure mass in a zero-g environment?