Every karat has a density fingerprint, and this chart tells you which fingerprints are honest and which ones overlap.
This reference is for counter staff, scrap buyers, and estate appraisers who want one page to check a densimeter result against. The numbers matter because karat bands are narrower than most people expect, and a result that looks close to 14K can quietly belong to a lead-heavy or white-gold recipe.
- Pure 24K gold is about 19.3 g/cm³; every alloying metal in jewelry is lighter, so density falls as karat falls.
- Same karat does not mean same density: 18K rose, yellow, green, and palladium white can span roughly 15.1 to 16.5.
- Tungsten sits at about 19.25 g/cm³, essentially on top of gold, so density alone can never clear a heavy bar.
Use ranges, not single points
Published SG values assume a nominal alloy. Real jewelry carries zinc, nickel, palladium, or silver in varying amounts, so treat each karat as a band of roughly ±0.3 to ±0.5 SG.
Solid metal only
A hollow link or a stone-set mount returns a falsely low number. If the piece is not provably solid, the chart does not apply to it.
Know the false friends
Tungsten carbide near 15.6 overlaps 18K, lead near 11.3 overlaps 9K and 10K, and tungsten near 19.25 overlaps pure gold.
Log the first pass
Write the density, the karat the unit displayed, and the stamp on the ticket. Disagreement between those three is your escalation trigger.
Typical density bands for yellow gold by karat
The physics is simple: density of an alloy is the mass-weighted blend of its ingredients, so more gold means a heavier piece for the same volume. Pure gold is about 19.32 g/cm³. A 22K coin alloy of gold and copper lands near 17.6, and a 22K with some silver sits slightly higher. Standard 18K yellow with equal silver and copper lands near 15.5. Drop to 14K and you are around 13.0 to 13.6, with zinc pulling the figure down in cast jewelry alloys.
These are ideal-mixing estimates, and real foundry alloys drift from them. A manufacturer who adds zinc for fluidity lowers density; one who adds more silver raises it. That is why the table below gives bands rather than a single figure, and why a reading within about 0.3 of the band center should be treated as a confident match while a reading 1.0 or more outside it should trigger a second look before you quote a price. Keep your own log of check-piece readings so you learn how far your local supply of scrap sits from the published bands.
- Silver-rich alloys read denser than copper-rich ones at the same karat.
- Zinc and nickel both lower density slightly compared with copper.
- Cast hollow-link chains can read far under the band even when the metal is genuine.
White, rose, and green gold change the number
White gold is the main source of confusion. Nickel-white 18K typically falls near 14.7 to 15.3, while palladium-white 18K can reach 15.9 or higher because palladium is denser than nickel at roughly 12.0 g/cm³. Rose gold is copper-heavy, so 18K rose reads lower, near 15.1, than 18K yellow. Green gold is silver-heavy and reads higher, near 16.0. For a buying desk the practical rule is to identify the color first, then pick the band. A white 14K ring reading 13.8 is not suspicious if the alloy is palladium-based, but the same number on a yellow ring needs a stamp check. When staff skip the color step, they either reject honest pieces or approve overpriced plated ones. Keep a laminated card at the bench with color-adjusted bands so the call takes seconds instead of a debate.
Use the color rule together with a quick weight sanity check. A thick white 14K band can read near 13.8 while a thin one reads closer to 13.2, because wear, solder, and rhodium plating add small mass differences that the display never reports. Photograph the piece and note its color beside the density on the ticket. After a few dozen purchases you will see that your own supplier mix clusters in predictable zones, and those local clusters are more useful than any published figure. Update the laminated card with your observed ranges once a quarter, and keep the old copy so you can see how the market you buy from has shifted.
Karat density chart and overlap traps
Use the chart as a screening aid, not a verdict. Values are approximate and assume solid, homogeneous metal at room temperature. Anything that falls between two bands, or that matches a lookalike material listed in the lower rows, should move to XRF, acid, or fire assay depending on ticket size. The overlap rows are the ones that cost shops real money, so read them before you rely on the rest. In practice, set two thresholds at the bench: a green zone where the reading sits inside the band and staff proceed, and a red zone where anything outside the band by more than about one density unit triggers a written escalation to a second test method. Everything between is a yellow zone that earns a re-run.
Think of the chart as three questions answered in order. Is the reading inside the band for the stamped karat and color? Does the piece have anything that breaks the solid-sample rule, such as stones, hollow sections, or heavy solder? And does the ticket value justify a second method regardless of the answer? Staff who ask those questions in sequence rarely get caught by an overlap row. Staff who read only the first number and quote a price are the ones who end up explaining a loss to the owner, usually on a piece that looked perfectly ordinary at the counter.
| Material | Approx. density (g/cm³) | Desk note |
|---|---|---|
| 24K / 999 gold | 19.3 | Bullion; tungsten fill is the main threat |
| 22K (91.7%) | 17.6 – 17.8 | Coins and Indian jewelry |
| 18K yellow | 15.3 – 15.6 | Rose near 15.1, green near 16.0 |
| 18K white (Ni or Pd) | 14.7 – 16.0 | Palladium alloys run higher |
| 14K yellow | 12.9 – 13.6 | Zinc lowers the figure |
| 10K yellow | 11.3 – 11.8 | Lead (11.3) overlaps this band |
| 9K yellow | 10.9 – 11.4 | Common in UK and Australian pieces |
| Tungsten | 19.25 | Overlaps 24K; density cannot separate them |
| Tungsten carbide | ~15.6 | Overlaps 18K gold |
| Gold-plated brass | 8.4 – 8.7 | Falls far below any gold band |
Recommended densimeters for this workflow
| Product | Best for | Price tier | Editor view | Amazon |
|---|---|---|---|---|
| Alfa Mirage GK-300 | Jewelry counters buying solid gold under ~250 g | Premium | Editor assessment: Excellent | Check Latest Price → |
| RODIETO 600 g Gold Purity Densimeter | Pawn and mixed jewelry intake with heavier solid chains | Value | Editor assessment: Strong | Check Latest Price → |
| Alfa Mirage GKS-300 | Mixed gold + platinum desks that need finer purity readouts | Premium | Editor assessment: Strong | Check Latest Price → |
Best Overall for Jewelry Desks
Alfa Mirage GK-300
- Best forJewelry counters buying solid gold under ~250 g
- Price tierPremium
- Editor viewEditor assessment: Excellent
Best Value / Best for Pawn Capacity
RODIETO 600 g Gold Purity Densimeter
- Best forPawn and mixed jewelry intake with heavier solid chains
- Price tierValue
- Editor viewEditor assessment: Strong
Best for Platinum / Finer Purity
Alfa Mirage GKS-300
- Best forMixed gold + platinum desks that need finer purity readouts
- Price tierPremium
- Editor viewEditor assessment: Strong
Best Overall for Jewelry Desks
Alfa Mirage GK-300
Key takeaways
- Best when solid jewelry stays under ~250 g
- Karat language staff can explain to customers
- Skip if heavy chains already crowd 300 g
Jewelry counters buying solid gold under ~250 g
You regularly buy heavy chains or bars over 300 g
Quick snapshot
Pros
- Karat modes built for gold buying—not a generic lab densimeter UI
- Japan-made brand that shop owners recognize for warranty optics
- Doubles as a gram scale so trade-ins stay on one footprint
- Non-destructive first pass—no acid stains on retail-ready pieces
Cons
- 300 g ceiling fails many pawn-weight solid chains
- Premium price vs generic 600 g Amazon kits
- Still cannot test hollow or gem-set jewelry (physics limit)
- Some buyers complain about learning the water-hang workflow on day one
Why we picked it
Why it earns the badge
We picked the Alfa Mirage GK-300 as the best overall starter for jewelry stores because it is built around karat language, not just a bare density number. On a retail counter, that matters more than most buyers admit on day one. A salesperson can take a solid trade-in, run the air weight and water weight, and talk in K14 / K18 terms the customer already understands—without translating a raw density chart mid-conversation. The Japan-made positioning also helps when an owner asks why you are not buying the cheapest no-name kit on Amazon. Warranty optics and brand familiarity reduce pushback from partners who have seen too many generic electronics fail after a few busy seasons.
Who it is ideal for
This machine is ideal if your solid intake mostly stays under about 250 g: rings, solid bracelets, light scrap lots, and estate pieces that are clearly solid metal. Treat the 300 g ceiling as a hard workflow limit, not a marketing number. If your desk routinely sees thick Cuban chains, stacked scrap bags, or solid pieces that regularly flirt with 280–300 g, capacity—not brand prestige—should win, and you should move to a 600 g shop densimeter before you outgrow the GK-300 mid-purchase.
Who should skip it
Who should skip it: pawn shops with heavy-chain days, coin desks handling bars, budget-first buyers who only need a rough karat band once a week, and anyone who thinks a densimeter will replace acid or XRF for hollow or gem-set goods. Manufacturer guidance is blunt on the physics limits: hollow jewelry, stone-set pieces, and metals with density very close to gold (including tungsten cores in bars) are outside the trustworthy zone. Those are not “bugs” in the GK-300—they are limits of Archimedes testing itself.
What real buyers get wrong
When you dig past star ratings on Amazon-style densimeter listings, the recurring 1-to-3 star themes are rarely “karat mode is fake.” They are operator and expectation problems: air bubbles clinging to textured scrap, the sample touching the tank wall, testing hollow electroformed jewelry that returns falsely low density, missing English manuals on generic kits, and buyers who expected an assay certificate instead of a first-pass screen. Train solid-sample rules on day one, keep distilled water and a soft brush at the tank, and use a written threshold for when density results escalate to XRF. Done that way, the GK-300 becomes a reliable buyer aid on a jewelry desk rather than a mysterious black box that staff avoid after one awkward customer conversation.
Key specs → desk benefits
300 g capacity / 0.01 g weight resolution
Stable enough for solid rings and most bracelets, with gram-scale precision that keeps scrap payouts honest.
K9–K24 karat + purity % modes
Staff can explain a karat band to a customer in one sentence instead of translating raw density charts.
Densimeter + scale in one unit
You avoid buying a separate jewelry scale for intake weighing on the same counter.
Best Value / Best for Pawn Capacity
RODIETO 600 g Gold Purity Densimeter
Key takeaways
- 600 g headroom for pawn-weight solid chains
- Shop-class 0.001 density without lab pricing
- Confirm seller, accessories, and exact capacity
Pawn and mixed jewelry intake with heavier solid chains
You need Japan-brand prestige more than usable capacity
Quick snapshot
Pros
- 600 g headroom covers most solid chain intake
- 0.001 g/cm³ density resolution is the shop-class sweet spot
- Karat / purity / density in one workflow
- Usually ships as a complete tank + hanger kit
Cons
- Generic brand—seller quality and support vary
- Listing titles can be noisy; you must confirm exact capacity
- Not a tungsten-proof bar tester on its own
- Lower brand recognition if ownership wants “made in Japan” optics
Why we picked it
Why it earns the badge
RODIETO’s 600 g class is our best value pick because capacity is the feature that actually saves pawn and mixed jewelry desks from buying twice. A beautiful 300 g branded unit that cannot weigh your heaviest regular chain is a failed purchase—no matter how clean the karat UI looks in the product photos. This kit targets the real workflow: solid scrap, solid chains, fast karat/density/purity screen, and a complete tank + hanger setup so you are not hunting accessories after the box arrives.
Who it is ideal for
Ideal for pawn shops, mixed jewelry buyers, and scrap desks where solid intake regularly lands between 200 g and 500 g. The 0.001 g/cm³ density resolution is the shop-class sweet spot: fine enough for solid karat banding without paying lab-SKU prices. Managers also get a second number (density or purity %) when karat mode looks off, which helps when a second staffer re-checks a disputed piece.
Who should skip it
Skip it if brand prestige is a boardroom requirement—“made in Japan” optics matter in some retail ownership conversations—or if you only ever buy light rings under ~150 g. In that lighter jewelry-only case, a 300 g premium unit may feel cleaner on a glass retail counter and leave more budget for training and distilled-water discipline. Also skip any densimeter as a standalone answer for bullion bars you suspect are tungsten-filled; density alone will not settle that fight.
What real buyers get wrong
Cross-check Amazon seller ratings and the in-box list (scale, tank, hanger, power, any claimed printer) before you checkout. Across generic 600 g densimeter listings, the honest low-star complaints cluster around missing English instructions, accessories that were pictured but not shipped, confusing multi-SKU titles, and buyers who tested hollow or gem-set jewelry then blamed the machine. Those are avoidable with a pre-purchase checklist: confirm capacity on the live listing, screenshot the accessory list, decline hollow/gem-set pieces at intake, and treat the result as a first pass. Do that, and a value 600 g kit like this becomes the workhorse most pawn desks actually need.
Key specs → desk benefits
600 g capacity
Fewer “piece won’t fit” moments on pawn days when solid chains run heavy.
0.001 g/cm³ density resolution
Fine enough for solid scrap karat banding without paying lab-SKU prices.
Karat + purity + density display
Managers can spot-check a second number (density) when karat mode looks off.
Best for Platinum / Finer Purity
Alfa Mirage GKS-300
Key takeaways
- Upgrade for platinum + finer purity—not more capacity
- Ideal after staff already know air/water workflow
- Wrong pick if heavy chains are the real bottleneck
Mixed gold + platinum desks that need finer purity readouts
You only need basic 10K/14K banding or need >300 g capacity
Quick snapshot
Pros
- Finer weighing supports tighter purity display than base GK-300
- Platinum tables help mixed precious-metal counters
- Lower minimum sample weight on the GKS class
- Same non-destructive solid-metal workflow jewelers already trust
Cons
- Same 300 g ceiling—no capacity upgrade over GK-300
- Costs more; overkill if you only screen broad karat bands
- Still blind on hollow / gem-set constructions
- Buyers who needed grams of capacity sometimes regret not buying 600 g instead
Why we picked it
Why it earns the badge
The GKS-300 is our pick when a jewelry desk already understands densimetry and needs finer purity—especially with platinum in the mix. Paying more for another 300 g machine only makes sense if resolution and metal tables are the bottleneck, not capacity. The GKS class is aimed at buyers who already trust the air/water workflow and want a tighter purity display plus platinum tables so mixed precious desks do not bounce between instruments mid-intake.
Who it is ideal for
Ideal buyer: estate jewelry shops, mixed gold/platinum buyers, counters that quote tighter purity on solid lots, and managers who already trained staff on solid-sample rules. If your real pain is heavy chains or small bars, this is the wrong upgrade path. Buying finer decimals on a 300 g load cell will not fix “piece won’t fit” days. Move to 600 g or 1200 g capacity first, then revisit finer resolution only if disputed near-pure lots justify it.
Who should skip it
Skip it if you are budget-first, still learning the air/water workflow, or only need broad 10K/14K banding for scrap payouts. In those cases the base GK-300—or a clear 600 g value kit—delivers more practical upside per dollar. Also skip it if you mainly handle gem-set fashion jewelry; finer resolution does not fix the mixed-density problem of stones and hollow links.
What real buyers get wrong
Honest buyer sentiment in this category often sounds like disappointment about capacity, not about the decimal places. Reviewers who needed grams of headroom regret spending premium money on another 300 g footprint. Others expect densimetry to settle tungsten-bar disputes and walk away frustrated—density of tungsten is too close to high-karat gold for Archimedes alone. Use the GKS-300 as a sharper first-pass tool for solid gold and platinum desk work, pair high tickets with XRF or assay policy, and you get the upgrade you paid for instead of a more expensive version of the wrong problem.
Key specs → desk benefits
0.001 g weight resolution / finer density class
Helps when you are comparing near-pure pieces or platinum marks where coarse banding feels sloppy.
Gold + platinum purity tables
One bench tool covers more of a mixed precious desk without switching instruments mid-intake.
Buying decision
A densimeter with karat and purity modes turns these bands into a one-glance result. Check the current listing for the GK-300 if your solid intake stays under about 250 g.
FAQ
Why does my 14K ring read 12.6 when the chart says 13?
Several things can explain it: a zinc-rich or nickel-rich recipe, a trapped air bubble, a hollow section, or a small sample where 0.01 g of weight noise moves density by 0.3 or more. Re-dry, de-bubble, and re-run before drawing conclusions.
Can I tell white gold from platinum by density?
Often yes: platinum alloys sit near 20 to 21.5 while white gold tops out around 16. Both fall in a clear gap, but only if the piece is solid.
Is a density chart enough to price scrap?
For a first pass on solid lots, yes. For high-value or suspicious pieces, confirm with XRF or assay, because tungsten, lead, and thick plating can all mislead a density-only decision.