Platinum sits so far above every white metal on the density scale that a clean reading is almost self-explanatory.
Jewelry and estate buyers who take platinum in alongside white gold and palladium need a simple, repeatable way to sort them at the bench. The upside is a wide density gap that makes first-pass sorting easy. The downside is that the wrong display mode will confidently mislabel a piece, so mode discipline is the real skill.
- Pure platinum is about 21.45 g/cm³, and common 950 alloys land between roughly 20.0 and 20.7 depending on the alloying metal.
- The densest white gold alloys top out near 16, which leaves a gap of more than 4 g/cm³ to the lightest common platinum alloy.
- Tungsten at 19.25 and 24K gold at 19.3 sit just below platinum 900 and 950 alloys, so near-miss readings in the 19 to 20 band deserve a second method.
Sort by density first
Run an unknown white metal in plain density mode before you pick a table. The number alone tells you which family to try.
Use the right table
A platinum table applied to white gold, or a gold table applied to platinum, produces a precise-looking wrong answer.
Remember the alloy partner
Pt 950 with ruthenium reads near 20.7, while cobalt and copper recipes read near 20.0. The mark alone does not fix the density.
Confirm with the hallmark
A 950 or 900 stamp plus a density in the platinum band is strong evidence. A stamp with a gold-band density is a stop sign.
The density gap that makes platinum easy to sort
On the density scale, white metals split into clear groups. Silver sits near 10.4 and palladium near 12.0, while nickel-white and palladium-white gold fall from about 14.7 to 16.0. Platinum alloys then jump to roughly 20 to 21.5, with pure platinum at 21.45 and iridium-alloyed platinum slightly above that. Because no common white jewelry metal lives between 16 and 20, a solid piece that reads near 20 or higher is almost certainly platinum-group, and one that reads near 15 is almost certainly white gold.
That gap is the reason densimeters are popular on mixed desks. Staff can sort a drawer of white rings quickly and spend XRF time only on the ambiguous ones. The trick is to remember that the gap exists only for solid metal. Hollow platinum is rare but real in lightweight fashion pieces, and stone settings pull the result down just as they do with gold. A low platinum reading is a reason to inspect and re-test, never a reason to downgrade the metal on the spot.
- Under 12.5: silver-class, palladium, or base metal.
- 14.7 to 16.0: white gold family.
- 19.9 to 21.6: platinum family.
- Between those bands: re-test, inspect, or escalate.
Mode selection on a mixed white-metal desk
Most shop densimeters offer a gold table, a platinum table, and a plain density display, and sometimes silver. The platinum or PT mode converts density into an approximate platinum purity, assuming a platinum-group alloy. If you feed it a 24K gold bar at 19.3, it will confidently report a low-purity platinum value. If you feed a Pt 950 ring into gold mode, it will exceed the gold table's upper range or show a nonsense karat. Neither error is the machine's fault, since it only converts the number it is given with the table you selected.
Build the habit of running density mode first, reading the number, and only then choosing the table. Write the chosen mode on the ticket next to the result. When the density falls in the 19 to 20 band, which overlaps 24K gold, tungsten, and some low-grade platinum alloys, use XRF or a conductivity test before settling on a verdict. Finer purity displays, such as those on the GKS class, help when you compare near-identical platinum alloys, but they do not solve the overlap with tungsten.
Platinum and white-metal density reference
The table collects the numbers most useful for sorting white metals at the counter. Alloy values are ideal-mixing estimates and will vary with the exact recipe, so treat them as bands rather than certainties. When a piece sits near the boundary between two rows, do not push the call. Run a second method. A short written rule for which readings trigger XRF or acid keeps the whole desk consistent regardless of who is on shift. Keep the solid-sample rule in force, record density beside any karat or PT readout, and escalate high-ticket or unstable results to XRF or assay rather than forcing a payout from a thin reading.
| Metal | Approx. density (g/cm³) | Sorting note |
|---|---|---|
| Platinum, pure | 21.45 | Reference value |
| Pt 900 / iridium | ~21.5 | Slightly above pure Pt |
| Pt 950 / ruthenium | ~20.7 | Common US alloy |
| Pt 950 / cobalt or copper | ~20.0 | Common jewelry casting alloys |
| Pt 900 / palladium | ~19.9 | Overlaps near tungsten territory |
| 24K gold | 19.3 | Wrong table gives low-purity Pt |
| Tungsten | 19.25 | Overlaps gold; needs another test |
| 18K white gold | 14.7 – 16.0 | Nickel or palladium alloys |
| Palladium 950 | ~12.0 | Clearly below gold bands |
| Silver / sterling | 10.4 | Clearly separate |
Recommended densimeters for this workflow
| Product | Best for | Price tier | Editor view | Amazon |
|---|---|---|---|---|
| Alfa Mirage GKS-300 | Mixed gold + platinum desks that need finer purity readouts | Premium | Editor assessment: Strong | 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 → |
| CUTANGELAR Densimeter Kit (Printer Option) | Desks that want a printed karat/density slip | Value | Editor assessment: Solid | Check Latest Price → |
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 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 Printed Customer Slips
CUTANGELAR Densimeter Kit (Printer Option)
- Best forDesks that want a printed karat/density slip
- Price tierValue
- Editor viewEditor assessment: Solid
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.
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 Printed Customer Slips
CUTANGELAR Densimeter Kit (Printer Option)
Key takeaways
- Specialty pick when printed slips matter
- Lock capacity + printer inclusion before checkout
- A slip documents a screen—not a fire assay
Desks that want a printed karat/density slip
You will not use a printer and hate multi-SKU listings
Quick snapshot
Pros
- Optional thermal printer for customer-facing slips
- Multiple capacity/resolution configurations
- Helps managers keep a paper trail of the screen
- Covers gold and platinum-style readouts on many configs
Cons
- Easy to order the wrong capacity SKU
- Printer adds cost and another thing to maintain
- A slip is not an assay certificate—set customer expectations
- Listing complexity frustrates rushed buyers
Why we picked it
Why it earns the badge
Choose CUTANGELAR-style kits when printed slips are part of the customer experience—pawn counters, some retail trade-in desks, and multi-location shops that want a consistent brand family with optional thermal printers. A printed karat/density slip will not turn densimetry into an assay lab, but it does give managers a paper trail during disputes and helps staff show the customer what the machine displayed without relying on memory alone. That is a real operational benefit when expectations are set correctly.
Who it is ideal for
Ideal for managers who want documentation, desks that already know they will use a printer weekly, and shops standardizing on one product family while picking 300, 600, or 1200 g per location. The flexibility is both the feature and the risk: multi-SKU listings make it easy to order the wrong capacity or resolution. Lock capacity, weight resolution, density resolution, and whether the printer is included before you click Buy—screenshot the Amazon option you selected.
Who should skip it
Skip it if you want the simplest possible Amazon order with one unambiguous SKU, or if nobody on the desk will actually use a printer. Paying for print hardware you ignore is a common regret. Also skip it as a “budget miracle” if the listing is confusing; a clearer single-SKU 600 g kit may save more money through fewer wrong orders than a slightly lower sticker price.
What real buyers get wrong
Across printer-option densimeter reviews, the sharpest complaints are predictable: no English instructions, printer pictured but not in the box, cheap-feeling build relative to the photo, and seller support friction on returns. Those are shopping problems more than Archimedes problems. Mitigate them by buying from sellers with strong recent feedback, confirming the accessory list in writing, and training staff that the slip documents a first-pass density screen—not a certified purity result. When you need printed customer slips and are willing to shop carefully, this family is the right specialty pick.
Key specs → desk benefits
Optional thermal printer
Lets you hand a customer a record of the densimeter screen during disputes—without claiming it is a lab assay.
Multi-capacity family
You can standardize on one brand family while picking 300, 600, or 1200 g for each location.
Buying decision
The GKS-300 pairs gold and platinum tables with finer purity display, which suits mixed precious desks. Check the current listing and confirm capacity matches your typical pieces.
FAQ
Can a densimeter tell Pt 950 from Pt 900?
Not reliably. Their densities overlap across alloy recipes, so use the hallmark and XRF for grade, and density for family.
Will a platinum ring read correctly in gold mode?
No. Use density or PT mode. A gold table cannot interpret a density above 19.3 sensibly.
What about iridium or osmium pieces?
They read even higher, near 22.5. They are rare in jewelry, but any reading above 21.6 on a solid piece deserves a second look.