An end cap — also known in the trade as a bullet end or cord end — is a small metal finding designed to terminate and protect the raw end of a stringing material, whether silk cord, leather thong, rubber tubing, or multi-strand beading wire. By enclosing the end of the material within a metal shell, the end cap simultaneously prevents fraying or unravelling, provides a clean aesthetic finish, and presents a loop or ring to which a clasp or jump ring may be attached. End caps are among the most fundamental components in bead stringing and knotted necklace construction.

Form and Construction

End caps are most commonly produced as small cones, cylinders, or tapered tubes, open at one end to receive the stringing material and closed — or fitted with an integral loop — at the other. The interior diameter of the open end is sized to match the cord or wire gauge it is intended to receive. Common interior diameters range from approximately 1.5 mm for fine silk thread up to 8 mm or more for thick braided leather or multi-strand constructions. The exterior profile varies by style: plain cylindrical forms suit contemporary and minimalist designs, while fluted, beaded, or granulated surfaces are available for more decorative applications.

Attachment of the stringing material is achieved by one of two methods. In glued construction, the cord end is inserted into the cap and secured with a jewellery-grade adhesive, typically a cyanoacrylate or two-part epoxy. In crimped construction — more common with beading wire — a small crimp bead or crimp tube is placed inside the cap and compressed with crimping pliers, mechanically locking the wire in place. Some end caps incorporate an internal crimp channel, combining both functions in a single component.

Materials and Finishes

End caps are manufactured across a broad range of metals to suit different price points and design requirements:

• Base metal (brass, zinc alloy, or copper) with plated finishes — gold plate, silver plate, gunmetal, or antique bronze — represents the most economical option and is widely used in fashion jewellery and craft applications.
• Sterling silver (925) end caps are standard in fine bead stringing, particularly for knotted pearl and gemstone necklaces, where the finding must harmonise with precious materials.
• Gold (typically 14 ct or 18 ct yellow, white, or rose) end caps are used in high-end jewellery, especially where the piece incorporates fine gemstones or cultured pearls of significant value.
• Gold-filled components offer an intermediate option, providing a thicker gold layer than simple plating at a fraction of solid gold cost.

Role in Bead Stringing and Knotted Work

In traditional knotted necklace construction — the technique used for fine pearl and gemstone strands — the cord is knotted between each bead to prevent loss if the strand breaks and to protect adjacent beads from contact abrasion. The end cap conceals the final knot and the tail of the cord, producing a professional termination that transitions smoothly to the clasp mechanism. Without an end cap or equivalent finding, the raw knotted end would be both visually untidy and structurally vulnerable.

In multi-strand beading wire work, end caps serve a similar function but are often paired with a crimp bead seated just inside the cap, the wire looped through the cap's integral ring and folded back before crimping. This creates a secure mechanical connection that, when properly executed, can withstand the tension loads typical of a worn necklace.

Selection Considerations

Choosing the correct end cap requires attention to three principal factors: interior diameter (must match the cord or wire gauge precisely — too loose and the adhesive bond is weakened; too tight and the material cannot be inserted cleanly), metal compatibility (the finding metal should be consistent with or complementary to other metal components in the piece), and loop orientation (some end caps present a side-exit loop, others an axial loop, affecting how the clasp hangs and moves). For leather cord in particular, a snug fit is critical, as leather compresses slightly under glue but may pull free if the cap is oversized.