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How Gold Is Calculated — Karat Guide (10K, 14K, 18K, 22K, 24K Explained)

Wondering how gold is calculated when selling jewelry, coins, or bars? This guide explains karat (K), gold purity, and how buyers typically estimate value based on purity, weight, and current market price. If you want an item-specific offer, start with an online appraisal or book a private appointment in Beverly Hills.

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What “Karat” Means in Gold (K vs. Carat)

In jewelry, karat (K or kt) measures how much of the metal is gold on a 24-part scale. For example, 24K means the alloy is measured as 24 parts gold out of 24 (the purity standard reference used in jewelry). The FTC consumer guidance explains that the karat mark tells you how much pure gold a piece contains.

Karat (K) = gold purity

Carat (ct) is different — it refers to gemstone weight (like diamonds), not gold purity.

Carat (ct) = gemstone weight

Gold Karat Chart (Quick Reference)

  • 24K gold = 24/24 gold = ~99.9% (reference “pure” jewelry standard)
  • 22K gold = 22/24 gold = 91.7%
  • 18K gold = 18/24 gold = 75.0%
  • 14K gold = 14/24 gold = 58.3% (often stamped 585)
  • 10K gold = 10/24 gold = 41.7% (often stamped 417)
  • 9K gold = 9/24 gold = 37.5% (often stamped 375, common in some markets)

In jewelry, purity may be shown as a karat mark (e.g., 14K) or as fineness (parts per thousand, e.g., 585). FTC guidance and U.S. jewelry marking rules discuss correct karat designation and representation of gold content.

Common karat levels and approximate purity

Karat vs. Fineness (Why You Might See 585, 750, 999)

Karat is a jewelry purity scale based on 24 parts.

Karat = parts out of 24

Fineness expresses purity in parts per thousand. For example:
  • 585 = 58.5% gold (roughly 14K)
  • 750 = 75.0% gold (18K)
  • 916/917 = ~91.6–91.7% gold (22K)
  • 999 or 999.9 = fine gold / very high-purity gold (often bullion context)

LBMA explains fineness as a measure used in precious metals and describes gold trading references in terms of fine troy ounces and purity.

Fineness = parts per thousand

How Gold Value Is Usually Calculated (Basic Formula)

Gold value is usually estimated from three core inputs:
  1. Purity (karat / fineness)
  2. Weight
  3. Current gold market price (spot/benchmark)

The simple idea

A simplified estimate often follows this logic:
  • Item weight × purity % = pure gold content
  • Then the pure gold content is compared to the current market price
  • The final buy offer can differ based on item type, condition, and business pricing model
this is an educational guide, not a guaranteed quote.

Simplified calculation logic (educational)

Two items with the same weight can have different offers if one is:
  • designer jewelry,
  • a collectible coin,
  • damaged scrap,
  • or includes diamonds/gemstones.

Why this is only a starting point

What Buyers Check When Calculating Gold

Buyers look for stamps (10K, 14K, 18K, etc.) and may also test items, especially mixed lots or unclear pieces.

1) Purity (karat mark / testing)

Accurate weight is essential. Small errors can change the estimate, especially across multiple items.

2) Weight (accurate measurement matters)

Gold jewelry, scrap gold, coins, and bars may be priced differently even at the same market gold price.

3) Item type (jewelry vs. scrap vs. coins vs. bars)

Gold prices move during the day, so timing can affect estimates and final offers.

4) Market timing

10K vs 14K vs 18K Gold — What Sellers Should Know

Lower gold content, often more durable due to a higher proportion of alloy metals. Common in some mass-market jewelry.

10K gold (41.7%)

A very common jewelry standard in the U.S. market, balancing gold content and durability.

14K gold (58.3%)

Higher gold content and often used in premium jewelry. Can carry different resale outcomes depending on brand, design, and condition.

18K gold (75.0%)

More common in certain international jewelry traditions and bullion contexts. High purity affects valuation, but item type still matters.

22K/24K (high-purity gold)

Why Jewelry Is Not Always Priced as “Scrap Gold”

A gold piece may be valued for more than its melt content if it has:
  • designer brand demand,
  • collectible/estate appeal,
  • strong condition,
  • or valuable stones.

Designer and estate pieces can follow a different value path

Gold jewelry with diamonds or gemstones should be evaluated as a whole item, not automatically treated as plain scrap.

Mixed materials need proper sorting

Common Gold Markings and What They Mean

Examples:
  • 10K / 10KT
  • 14K / 14KT
  • 18K / 18KT
  • 22K
  • 24K

Karat stamps

A stamp is helpful, but buyers may still verify purity, especially for older items, mixed lots, or unclear markings.

Important note

Examples:
  • 417 (≈10K)
  • 585 (≈14K)
  • 750 (18K)
  • 916 / 917 (≈22K)
  • 999 / 999.9 (fine gold, often bullion)

Fineness stamps

How to Prepare Gold for an Appraisal

Keep jewelry, coins, bars, and scrap in separate groups if possible.

Separate by item type

Matching items (bracelet + necklace, etc.) may be easier to evaluate as a group.

Keep sets together

If jewelry includes stones, don’t dismantle it before appraisal — it can reduce value or complicate evaluation.

Don’t remove stones yourself

Send photos and details for a quick estimate before visiting.

Start online first (optional)

FAQ — Gold Karat Guide

Ready to Sell Gold?

Now that you know how gold is calculated by karat, the next step is getting an item-specific offer. We buy gold jewelry, scrap gold, coins, bars, and bullion with clear explanations of how value is determined.
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