Jewellery is the hardest category in outfit search, and the reason is arithmetic rather than anything clever.
Snagfit downscales every upload to 1280 pixels on the longest side. A necklace in a full-length photo occupies a small share of that, so what the description gets written from is a few dozen pixels of metal. From that you can establish the category and the colour. You cannot establish which piece it is.
Everything below is about what to expect at that size and how to get a better frame.
What survives at that size?
Two fields, reliably, and a third when the piece is large.
Metal colour is the most reliable field available in the whole category. Gold, silver, rose gold and gunmetal are separate product categories, and metal is bright against skin and fabric, so its colour survives compression and poor light better than almost anything else in a photograph.
Category survives, meaning necklace, earring, bracelet, ring, brooch. These have distinct positions on the body, and position alone identifies them.
Outline survives when the piece is big. A statement earring, a wide cuff bracelet, a chunky chain or a large pendant has enough shape to be read, and shape is what separates one piece from another within a category.
What does not survive is everything else: the stone cuts, the chain link type, the clasp, the setting, the finish. Those need a closer frame.
Which pieces are effectively unfindable?
Four cases, and they share one cause.
Fine chains. A delicate necklace at any distance is a line, and a line carries no information beyond its colour and roughly its length.
Small studs. An earring a few millimetres across in a full-length photo is a bright dot.
Thin rings. Same problem, worse, because hands are usually in motion and often partly out of frame.
Anything low-contrast against skin. This is the one people do not anticipate. Contrast is what defines an edge in a photograph, so gold jewellery on warm skin, or silver on pale skin in cool light, produces a soft boundary. Snagfit describes what it can distinguish, so a low-contrast piece may be missed entirely rather than described badly. It simply is not in the results.
That last case explains a lot of "why did it not see the necklace" questions. The necklace was there and the picture did not separate it from the person.
How close does the crop need to be?
Close enough that the piece takes up a real share of the frame.
For a necklace, that means cropping to the neck and shoulders. For a bracelet or a ring, to the hand and wrist. For earrings, to the head.
The limit is the resolution of the original. If a photo is 1080 pixels wide and the necklace occupies 50 of them, cropping to the neck gives you an image that is 50 pixels of necklace enlarged, which contains exactly as much information as it did before. Cropping cannot add detail that was never captured.
So the honest test is: does the original photograph have enough pixels to survive this crop. If it does not, the answer is a different photograph rather than a better crop. That is the same conclusion as finding sunglasses from a photo, and jewellery is the more extreme version of it.
Are watches different?
Yes, and they are the accessory that searches best.
A watch has real structure. The case shape, whether round, square, cushion or tonneau. The bezel, and whether it is plain, fluted, or marked. The dial layout, including where the numerals sit and whether there are sub-dials. The strap, which splits into bracelet, leather, rubber and fabric, each with its own subtypes. The crown position.
That is five fields on a piece that is normally larger than a ring or an earring and usually photographed on a raised wrist, which puts it closer to the camera.
A clear photograph of a wrist with the face visible often identifies a watch to a specific range. Getting to a single model usually needs the dial detail, which requires a close frame, but the range is often enough to shop from.
What about hats, scarves and belts?
These search far better, because they are fabric and they are large.
A hat is identified by its crown shape and its brim. Fedora, bucket, baseball cap, beanie, flat cap, boater, wide-brim: all distinct outlines, all named terms that retailers use. Material and colour read normally. Hats are one of the easier accessories.
A scarf is identified by size, material and pattern. It carries the same pattern problems as any printed garment, covered in why patterns are harder to match, but the fabric and the drape read well and a large scarf occupies enough of a frame to be described properly.
A belt is identified by width, material and buckle. The buckle is the most distinctive part and it is also the part most often cropped out or hidden behind an arm or a bag. A visible buckle changes a belt search a great deal.
All three of these behave more like clothing than like jewellery, which is the practical point: they are big enough for the normal rules to apply.
What can no photograph tell you?
Whether the metal is real, and that is where most of the price range sits.
Solid gold, gold plate, gold fill, vermeil and gold-coloured base metal all look identical in a photograph. The same applies to sterling silver against silver-plated and stainless steel. The difference is composition, and composition has no appearance.
The same is true of stones. A diamond, a moissanite, a cubic zirconia and a good glass stone are difficult to distinguish in a photograph even at close range, and impossible at outfit-photo distance.
Which means a jewellery search can return results spanning a very wide price range for what looks like one piece, and the thing separating them is the material stated on the listing. That is a fact about the category rather than about the search, and it is exactly the situation reading a shopping result describes: a very wide spread means the description was necessarily generic.
The listing will state the metal, the carat, the weight and the stone. Those four resolve the price range, and what to check before buying covers the rest.
Does layered jewellery make it harder?
It makes each individual piece harder and the overall look easier.
Several necklaces worn together at different lengths read as one arrangement rather than as three products. The chains overlap, the pendants sit against each other, and the boundaries between them are exactly the low-contrast edges that a photograph struggles with.
So a stack of three fine chains usually comes back as one necklace, or as a general description of layered gold chains.
The overall look is easier because layered jewellery is sold that way. Many retailers sell multi-strand pieces and layered sets, so a search for the arrangement often finds something closer than a search for any one component would.
Stacked rings and multiple bracelets behave the same way. If what you liked was the effect rather than one piece, searching for the effect is the shorter route.
What about jewellery in a close-up photograph?
Everything above changes, because the arithmetic changes.
A close photograph of a hand, a wrist or a neck gives the piece most of the frame, which means most of the 1280 pixels. At that point the chain link type, the setting, the stone cut and the clasp all become readable, and the search narrows accordingly.
This is why product photographs and detail shots search so much better than outfit shots. If the source is a video or a set of images, a close frame of the jewellery often exists, and finding it is worth more than any amount of work on the wide shot.
It is also why photographing your own jewellery works well. Hold it against a plain surface, in daylight, filling the frame. That is close to how a retailer photographs it, and the results reflect that.
What is the realistic goal?
Category and style rather than the specific piece, most of the time.
If you saw a chunky gold chain necklace and you want a chunky gold chain necklace, that is an achievable search and the results will be useful. Pick on price, on metal and on length.
If you want that exact necklace, you need a close photograph, and usually you need to know the brand. The route there is the same as everywhere else: find a better frame, ask the person, or work out the brand and search their catalogue directly.
Jewellery is also the category where building an outfit around one piece is most relevant, because a jewellery search that returns the right style at a range of prices is genuinely useful even when it does not return the piece.