8g thru 00g are domed on both ends
8g thru 1/2" have an approx 3/8" wearable between flares
7/16" thru 1" have one flat side and one domed side
9/16" thru 1" have an approx 7/16" wearable area between flares
Jewelry is measured through a gauge system (see chart below). The higher the gauge number the smaller the wire is. A standard "earring" is usually 20 gauge. Jewelry gauges/sizes can vary between manufacturers. There is no universal regulation on companies to make a standard size in body jewelry. A big part of this is that some jewelry is made overseas and measured in millimeters. And in the USA jewelry is measured in inches/gauges. So many times jewelry can be anywhere from .5mm to 1mm different.