Jewelry that has been formed by striking gold, silver or platinum sheet in a die or between two dies is die struck. This compresses the molecules and forces the metal into every crevice of the die. The result is a highly detailed, strengthened metal object that easily takes a high polish.
Die struck rings were normally produced by taking a blank, a flat piece of formed metal, and striking it into an engraved metal die. The pattern was forced into the metal, and the process often produced high quality mountings that held up very well over the years. The mounting would be formed into a ring shape by additional striking or forming. The weight/pressure of the presses used varied, as did quality. Many firms used the same dies for decades, and at least one firm actually still produces rings from dies that date back to the early 20th century, and may even use some 19th century dies. Molds and models can also be made from the dies, allowing rings of similar style to be cast. While resembling the die struck originals, a cast ring may not wear as well. Casting quality can vary widely.
Below you can view a 2 part promotional video of Jabel, an American jewelry manufacturer who uses die striking. You will have to look through the promotional aspect but the video shows the die striking process in detail and therefore is worth watching.