What does 14KP mean on gold jewelry?
Published October 10, 2026 · updated October 10, 2026
A “14KP” stamp is a 14-karat mark with one more letter. In the jewelry trade, the P is read as “plumb”, and the full mark is read as “14 karat plumb”. A seller uses it to say that the gold is not below 14 karat. That reading is trade usage. The letters “KP” and the word “plumb” are not in the federal statute on gold marks, and they are not in the FTC guide section on gold content. This page shows what the statute does say, how far below a mark the gold can test, and how that relates to the 0.585 purity that our gold calculator uses for 14K.
What the federal statute says
The federal rule is 15 U.S.C. 295. An official copy is at govinfo.gov. We read the two copies on October 10, 2026. The section applies to articles “made in whole or in part of gold or of any of its alloys” that are imported, exported, mailed or moved in interstate commerce. It sets two tests.
The first test is on a part of the article that has no solder. The statute says:
“the actual fineness of such gold or alloy shall not be less by more than three one-thousandth parts than the fineness indicated by the mark”
The second test is on the full article with its solder, “assayed as one piece”. The statute says that this fineness:
“shall not be less by more than three one-thousandth parts, in the case of a watchcase or flatware, or than seven one-thousandth parts, in the case of any other such article, than the fineness indicated by the mark”
The statute says that the two tests are “concurrent and not alternative”. An article must pass the two tests.
The FTC guide section 16 CFR 23.3 refers to the same numbers. It says that its marking provisions “are subject to the applicable tolerances of the National Stamping Act”. Its footnote says that gold parts “that contain no solder have a permissible tolerance of three parts per thousand”, and “If the part tested contains solder, the permissible tolerance is seven parts per thousand.”
The lowest fineness that each mark permits
A karat is one part in 24. The nominal fineness of a karat mark is the karat number divided by 24 and multiplied by 1,000. The table subtracts the statute tolerance from that number. All values are parts per thousand, rounded to one decimal place.
- “Minus 3” is the lowest result for a part without solder. It is also the lowest result for a full watchcase or flatware article with its solder.
- “Minus 7” is the lowest result for any other full article with its solder.
| Mark | Nominal | Minus 3 | Minus 7 |
|---|---|---|---|
| 10K | 416.7 | 413.7 | 409.7 |
| 14K | 583.3 | 580.3 | 576.3 |
| 18K | 750.0 | 747.0 | 743.0 |
The results in the table are our arithmetic. The statute gives the tolerance. It does not give these results.
14KP against the tolerance
In trade usage, a plumb mark says that the seller does not use the tolerance. For 14KP that is a claim of 583.3 parts per thousand or more. The statute has no separate rule for a mark with the letter P. It measures each article against “the fineness indicated by the mark”.
Why this site uses 0.585 and not 583.3
There are two numbers for 14K, and they are not the same number.
- 14 divided by 24 is 583.3 parts per thousand. This is the nominal fineness of a 14K mark.
- 585 is the three-digit fineness mark. Our calculators use 0.585 for 14K.
585 is 1.7 parts per thousand above 583.3. The statute does not contain the number 585. For an article with the 585 mark, the same arithmetic gives 582.0 without solder and 578.0 for the full article with solder. For a watchcase or flatware, the result for the full article is 582.0.
Our calculators use 0.585 for each 14K item, and they use the same value for a 14KP item. An item that tests at 580.3 has 0.8% less gold than the 0.585 estimate. An item that tests at 576.3 has 1.5% less. An estimate from a stamp is not a test result. The guide to karat stamps lists the other marks.
Common questions
Is 14KP worth more than 14K?
Our calculators give the same melt-value estimate for the two marks, because they use 0.585 for each. This page has no data on the offers of buyers.
Does the P mean plated?
16 CFR 23.3 gives the terms for coated products, for example “Gold Plated”, “Gold Filled” and “Gold Electroplate”. The letters KP are not in that section. To examine an item, see how to tell if gold is real.
What about 10KP and 18KP?
The trade reading is the same, 10 karat plumb and 18 karat plumb. The table gives the nominal fineness and the tolerance results for the two marks.
This page is general information. It is not legal advice.