A locket is not a pendant. It is a tiny room that opens, and the engineering has to keep the door shut while letting the owner open it ten times a day. We make more lockets around Mother's Day and the winter gifting window than the rest of the year combined, and every commission starts with the same three questions: what goes inside, who wears it, and how often will it open.
The shape decision
Oval, round, heart and rectangle are the four shapes we make most. Oval is the default because it fits a cropped portrait photo and hangs flat on the chest. Heart is the gifting default for romantic and mother-child pieces, but it is harder to engineer because the two sides of the heart have to close flush, which means a tighter tolerance on the hinge. Rectangle sits modern and geometric, and it fits two photos side by side. Round is the rarest, chosen for clients who want a coin or medallion feel.
The size follows the photo. A standard wallet photo cropped to a 20 mm oval fits a locket that is 22-25 mm tall. A heart locket that looks generous on the CAD is often too small for a face; we size to the photo, not to the thumbnail. We cover pendant proportions more broadly in pendant design and chain length.
The photo slot: what actually fits
Every locket has two slots, one on each inside wall, or one slot with a small window on the front. The slot is cut to a specific size, and the photo has to be cropped to match. We send a printable template with every locket order so the client can print and cut the photo at home, rather than guessing and trimming it in the locket. A photo that does not sit flat will warp the hinge and break the closure over time. We also note that laser-printed photos are better than inkjet, because inkjet ink bleeds in humidity. If the photo is a loved one's handwriting, we scan it, reverse it, and set it so it reads through the window; that process is the same one we use for handwriting engraving.
Hinge, bail and chain
The hinge is the part that fails. We use a barrel hinge with a separate pin, rather than a folded hinge, because it lasts through 10,000 opens. The bail is the loop the chain goes through; on a locket over 20 mm, we spec a double bail so the piece sits flat on the chest instead of twisting. Chain choice follows the weight: a 5 g locket on a 1 mm cable chain looks right; the same locket on a 2 mm Figaro chain looks clunky. We cover chain choices in bespoke pendant necklace design.
Engraving on a locket
There are three places to engrave. Outside front: a name, a date, or a small crest. Machine engraving fits 10-15 characters on a 25 mm front; hand engraving a crest takes a separate sitting. Outside back: a longer inscription, 20-30 characters, which is the most common choice because it is private. Inside: a tiny line next to the photo slot, usually a date or a single word. Inside engraving is shallow and we keep it short, because the photo slot wall is thin. We cover font choices more broadly in engraving fonts and long text.
We mark the locket with the karat stamp and maker's mark on the inside rim, away from the photo slot, consistent with the 16 CFR Part 23 marking rules and the FTC Jewelry Guides. If the locket is a gift, we pair it with a bespoke gifting voucher so the recipient can choose the chain length.
FAQ
What size photo fits in a custom locket?
We send a printable template with every order. Most 25 mm oval lockets fit a 20 x 15 mm cropped photo. We design the slot around the photo you send, so you never have to trim a face.
Can I put two photos inside?
Yes. Most lockets have one slot on each inside wall, so two photos, one per side. A front-window locket shows one photo through the front and holds a second behind it.
Will the locket pop open on its own?
We use a spring closure with a safety notch, tested to stay shut through normal movement. If a locket pops open in the first year, we adjust or replace the closure under our care plan.
Can I engrave handwriting on the front?
Yes. We scan the handwriting, size it to the front, and engrave it by hand. It is one of the most requested details, and it is what turns a locket into a keepsake rather than an accessory.
Want a locket that actually holds the photo you have in mind? Book a 20-minute sitting and bring the photo (or a high-res scan). We will size the locket to the photo on the spot, choose the shape and chain, and quote it in writing within 48 hours. We also keep blank lockets in stock for rush gifting. Trade retail partners: our locket spec sheet lists slot sizes by shape and hinge type, so your team can promise a fit before the order goes in.
