Gold Refining for Jewelers: Lemel, Sweeps & Polishings
By Isaac (Sahag) Makdessian, Owner and Head Refiner at Bay Area Metals. Operating the family-owned South San Francisco refinery since 2012. Specialist in gold, silver, platinum, and palladium refining for public sellers and Bay Area trade clients.
Key Takeaways
Gold refining for jewelers recovers the metal a bench loses at every abrasive step: filing, sawing, sanding, polishing. The trade sorts that byproduct into two classes, meltable metal and burnable sweeps, each processed differently (Ganoksin / David H. Fell & Co.).
A bench produces three practical streams. Lemel (filings and shavings) and casting scrap are meltable and assay directly. Polishing dust and floor sweeps are burnable and must be incinerated and screened first. Manufactured 14k polishing sweeps can assay as high as 4% gold by weight (Ganoksin).
Keeping streams separate protects your payout. Mixing karats, sharing buffs between gold and platinum, or dumping filings into sweeps all lower the assay you get paid on.
At Bay Area Metals you watch your own lot weighed, assayed by XRF or fire assay, and smelted on-site at 154 South Spruce Ave, South San Francisco CA 94080, then take payment as cash, wire, or casting grain in the karat you use.
Refinery-direct pays up to 99% of the daily LBMA spot price for gold. A South San Francisco bench can drop off, watch the assay, and settle the same or next day instead of mailing scrap out of state.
Where does a jewelry bench lose gold, and can you recover it?
A working bench loses gold at nearly every abrasive step, and almost all of it is recoverable. Cutting, filing, sawing, sanding, and polishing each shed metal that ends up in the bench pan, the sweeps, and the polishing dust. Over a month of production that adds up to a weight of gold worth refining rather than sweeping into the trash.
The refining trade sorts that byproduct into two classes. According to the jewelry-industry reference Maximizing Refining Returns (Ganoksin, by Robin White and David H. Fell & Co.), everything off a bench is either meltable or burnable. Meltable material is predominantly metal: trees, sprues, buttons, filings, and substandard inventory that can be melted, sampled, and assayed as-is. Burnable material is the sweeps: polishing dust, floor sweeps, and ultrasonic sludge that has to be incinerated and screened before its gold content shows up in an assay.
That is why a bench should treat its scrap as inventory. The metal in your pan was paid for once, when you bought the casting grain; refining is how you get paid for it again instead of losing it. This piece covers the three streams a bench produces, how to collect them so they pay the most, and what happens when they reach the Bay Area gold refinery floor.
The three streams: lemel, bench sweeps, and polishing dust explained
For a working jeweler, bench scrap breaks into three streams: lemel and casting scrap (meltable metal, assayed directly), and polishing dust and floor sweeps (burnable, screened before assay). Each carries gold, but each reaches the refinery in a different form, and knowing which is which is the first step to getting paid fully for it.
Lemel is the fine filings and shavings that fall as you work metal at the bench: the residue of sawing, filing, and finishing. It is nearly pure bench metal, so it is meltable and assays directly. Lemel is the highest-grade byproduct most benches produce, which is why goldsmiths have collected it in a bench skin or pan for centuries.
Bench and floor sweeps are the broader collection: sweepings from the benchtop and the floor around it, mixed with the grit and dust of a working shop. Sweeps can hold recoverable gold, but they arrive mixed with non-metal, so they are treated as burnable and screened before assay.
Polishing dust (polishings) is the material thrown off by buffing and polishing wheels, captured in a dust-collection system or a filter. It looks like nothing but grey powder, yet it carries real value. Manufactured 14k gold polishing sweeps can assay as high as 4% gold by weight, according to Ganoksin's refining reference. On a shop that polishes daily, that 4% accumulates into a lot worth sending in.
Alongside these three, most benches also generate casting scrap: sprues, buttons, trees, and failed inventory. That is straightforward meltable metal, the easiest of all to assay and pay on.
Why keeping your streams separate pays more
Separating your scrap by type and karat almost always nets more than handing over one mixed bin. The reason is simple: an assay pays on measured purity, and mixing drags that number down or slows the process that establishes it.
Ganoksin's guidance to manufacturers is direct on this point. Bench filings should be kept separate from trees and sprues, and separated by alloy type, because contaminants from one alloy shouldn't be introduced into another. The classic and costliest mistake is letting gold and platinum share the same polishing buffs or filings bin. Platinum embedded in a gold lot, or the reverse, forces extra processing and muddies the assay of both.
For a smaller Bay Area shop this doesn't mean a laboratory regimen. It means a few labeled containers, one each for lemel, casting scrap, and polishing dust, plus a rule that platinum work stays on its own buffs and bin. That habit costs nothing and is the difference between a clean assay and an averaged-down one. When you bring a lot in, we will tell you honestly whether it is worth assaying a piece separately or smelting it together before anything goes in the furnace.
How does gold refining for jewelers turn bench scrap into a payout?
Once your lot arrives, it moves through weighing, assay, smelting, and payout, and as a trade client you are welcome to watch every step. That transparency is the point of using a local refinery rather than a mail-in service.
The sequence depends on the stream. Meltable metal, your lemel and casting scrap, is logged and weighed in front of you on a calibrated scale, then melted into a homogeneous mass so its true blended purity can be read. Burnable sweeps and polishing dust take an extra step first: they are incinerated and screened to concentrate the recoverable content, then sampled and assayed. For a fast, non-destructive read we use X-ray fluorescence (XRF); for higher-value lots we run a fire assay by cupellation, the most accurate method for pinning down exact gold content.
Then the math is shown to you before you decide: the day's spot price, times the assayed purity, times the weight, minus the small deduction for assay and refining loss. Nothing is pulled from the air, which is the same standard our authority guide on how refining works covers in full. You see the weight, the assay, and the payout before any metal changes hands.
Refinery-direct versus the middleman: what your bench scrap is worth
A refinery pays the highest percentage of spot because there is no one standing between your scrap and the smelter. Bay Area Metals publishes a payout range of up to 99% of the daily LBMA spot price for gold. A gold buyer, pawn shop, or broker who buys your scrap is going to resell it to a refinery anyway, and the gap between what they pay you and what they collect is their margin.
The worked example makes it concrete. Say a bench accumulates 100 grams of mixed 14k lemel and casting scrap over a quarter. At 58.3% gold, that lot holds about 58.3 grams of pure gold, or 1.87 troy ounces. On a day when spot gold is near $4,000 per troy ounce (verify the live LBMA gold price before applying this to a real lot), that is roughly $7,500 of gold. A refinery paying near the top of its published range settles that lot within a few percent of $7,500, minus the assay deduction. A buyer paying 70% of spot hands you around $5,250 and keeps the rest. On one quarter's bench metal, refinery-direct is worth roughly $2,000 more to that shop.
"I'm a jeweler/goldsmith and have dealt with many refiners. Bay Area Metals are the most upfront and honest with the highest payout. I just moved here from NYC and am really happy I can take my scraps here." - Jennifer N., Brooklyn, NY, customer testimonial, bayareametals.com
You can also skip cash entirely and exchange refined scrap for investment-grade casting grain or bullion in the karat you use, closing the loop between what leaves the bench and what comes back as usable metal. A lot of Bay Area benches treat us as supplier and refiner at once for that reason.
Four questions to ask before you hand over your scrap
Before you choose a refiner, ask four questions: Do you get a sample for your own assay? Can you witness your material being processed? Do you get paid for your oversized material, the pieces screened out of sweeps? And what are the settlement times? Ganoksin's refining guide poses these four to manufacturers, and they are worth asking of anyone who wants your metal.
For reference on the last one, standard gold refining settles anywhere from an immediate exchange up to about ten days, while sweeps typically take two to four weeks, per the same source.
Our answers are the reason bench jewelers across the Bay Area drive their scrap to South San Francisco. You watch your lot weighed, assayed, and smelted on-site. Oversized material screened from your sweeps is returned or paid on, not quietly kept. Most metallic lots settle the same or next day. Bay Area Metals carries an A+ rating with the Better Business Bureau and a 5.0 Yelp rating from over 60 published reviews.
"All the jewelers come here to sell their gold for melting purposes. This place offers you the best prices! Isaac the owner is friendly and professional. The whole transaction is painless and fast!" - Debbie G., Millbrae, CA, customer testimonial, bayareametals.com
Glossary (quick reference)
Lemel - The fine filings and shavings collected at a jeweler's bench. Nearly pure bench metal; meltable and assayed directly.
Bench and floor sweeps - Sweepings from the benchtop and surrounding floor, mixed with shop grit. Treated as burnable and screened before assay.
Polishings (polishing dust) - Material thrown off by buffing wheels, captured in dust collection. 14k polishing sweeps can assay up to 4% gold by weight (Ganoksin).
Casting scrap - Sprues, buttons, trees, and old inventory. Straightforward meltable metal.
Meltable vs burnable - The refining trade's two classes of bench byproduct: solid metal that is melted and assayed, versus sweeps that are incinerated and screened first.
Frequently Asked Questions
Author
Isaac (Sahag) Makdessian is the owner and head refiner at Bay Area Metals, the family-owned precious-metals refinery at 154 South Spruce Ave, South San Francisco CA 94080. The business has operated in the Bay Area since 2012, refining gold, silver, platinum, and palladium for public sellers and for the region's jewelry, dental, pawnshop, electronics, and solar trades. Bay Area Metals carries an A+ rating with the Better Business Bureau and a 5.0 Yelp rating from over 60 published customer reviews. Author archive
Ready to refine? Schedule a Bay Area refinery pickup
If your bench generates lemel, sweeps, and polishings, the fastest way to see what they are worth is to bring a lot in. Text or call (650) 675-5009, or visit 154 South Spruce Ave, South San Francisco CA 94080, to set up a trade consultation or a recurring pickup for higher-volume shops. Bring a representative sample of your scrap and your ID. You will see the weight, the assay, and the payout math before any metal changes hands. See how we serve the industries we work with to get started.