How it’s made: Ram’s Horn Studs

how to cast silver earrings from shells

A ram’s horn shell is an unusual find along the shores of the Atlantic. This shell is the chambered internal shell of a deep sea species of squid called the Spirula spirula that is a close relative of the nautilus. Rarely seen in the wild, it’s one of the most unusual cephalopods out there (see page 66). The ram’s horn earrings are made from molding and casting a beach-found, washed-up shell in recycled silver.

making a mold of a seashell for jewelry casting

I collected the shell on a beach in Delray, Florida, and then had a silicone mold made of the original shell (above left).

I used the mold to produce a wax model by pouring wax into the silicone mold (1).

The wax model was then used to make a second mold for the metal (2).

process of casting silver sea shell

I refined the wax model by cutting off the end of the spiral and making the back smooth and flat (3). These changes create a shape that works better for small earrings.

I added a wax sprue to the back (4). A sprue creates the channel through which the molten metal can be poured into the final “investment” mold. The investment mold is created by putting the wax model into a fluid investment material—much like plaster—that sets around the wax pattern. When the investment material is completely set, the mold is heated and the melted wax is poured out of the mold, in a process called “the lost wax casting process.”

I then poured molten sterling silver into the investment mold. Once the metal was cooled, I removed it from the investment mold (5), and I cleaned off the rough edges from the cast metal (6).

finishing a sterling silver cast seashell earring

I stamped my brand and sterling silver metal hallmark on the back where the sprue connected to the shell (7).

I then drilled a small clean recess for the earring post in the center of the back of the silver shell (8).

seashell earrings

I then soldered on the earring post using a 4,000°F acetylene torch (9). Using the same wax mold, I can make many investment molds and cast any number of silver shells.

The earrings then went into a mildly acidic “pickle bath” to clean up from the soldering process, and they came out clean and smooth (10).

I polished the earrings on a buffing lathe using multiple grits of silicone wheels (11), and tumbled them with water and steel shot (12) to give them a high shine (13).

sterling silver cast sea shell earrings

This article appeared in the Beachcombing Magazine March/April 2021 issue.

Leave a comment

All comments are moderated before being published