Gold filled (GF) is a jewelry industry term for a layer of karat gold mechanically bonded to a base metal core. It's a more affordable alternative to solid gold but offers significantly more durability and value than gold plated items. The term "gold filled" means that the visible surface of the jewelry item contains a significant amount of gold. The US Federal Trade Commission (FTC) requires that an item labeled "gold filled" must have at least 1/20th (or 5%) of its total weight in 10K or 14K gold.
How Gold Filled Items Are Made
Gold filled items are typically created by heating a gold alloy and a base metal (like brass) and then bonding them together under extreme pressure. This process creates a thick, durable layer of gold that is bonded to the core. Unlike gold plating, where a very thin layer of gold is electrochemically deposited, gold filling involves a much thicker layer of gold that is mechanically attached.
The Math Behind the Calculator
This calculator helps estimate the intrinsic value of the gold content within a gold filled item. The calculation is based on the following logic:
Calculate the Weight of Gold: The total weight of the item is multiplied by the percentage of gold content (as a decimal) to find the actual weight of the gold in the item. For example, if an item weighs 10 grams and is 5% gold filled (1/20th GF), the weight of gold is 10 grams * 0.05 = 0.5 grams.
Calculate the Value of Gold: The weight of the gold (in grams) is then multiplied by the current market price of gold per gram. If the gold weight is 0.5 grams and the current price is $65.20 per gram, the value of the gold content is 0.5 grams * $65.20/gram = $32.60.
The formula used is:
Estimated Gold Value = (Item Weight in Grams * (Gold Percentage / 100)) * Current Gold Price per Gram
Use Cases for This Calculator
Jewelry Appraisal: Estimate the scrap value of gold filled jewelry, especially when considering selling or trading it.
Inventory Valuation: Businesses that deal with jewelry can use this to get a baseline value for their gold filled stock.
Consumer Information: Helps consumers understand the underlying value of the gold content in the jewelry they purchase or own.
Comparison: Allows for a quick comparison of the gold content value across different gold filled pieces.
It's important to note that this calculator provides an estimate of the *intrinsic gold value*. The actual market price of a gold filled item can be higher due to craftsmanship, design, brand, and other non-gold components or labor costs. This calculator focuses purely on the weight and purity of the gold itself.
function calculateGoldFilledValue() {
var itemWeightGrams = parseFloat(document.getElementById("itemWeightGrams").value);
var karat = parseFloat(document.getElementById("karat").value);
var goldPercentage = parseFloat(document.getElementById("goldPercentage").value);
var currentGoldPricePerGram = parseFloat(document.getElementById("currentGoldPricePerGram").value);
var resultValueElement = document.getElementById("result-value");
// Clear previous results and error messages
resultValueElement.textContent = "$0.00";
// Input validation
if (isNaN(itemWeightGrams) || itemWeightGrams <= 0) {
alert("Please enter a valid positive number for Item Weight.");
return;
}
if (isNaN(karat) || karat <= 0) {
alert("Please enter a valid positive number for Karat.");
return;
}
if (isNaN(goldPercentage) || goldPercentage <= 0) {
alert("Please enter a valid positive number for Gold Percentage.");
return;
}
if (isNaN(currentGoldPricePerGram) || currentGoldPricePerGram < 0) {
alert("Please enter a valid non-negative number for Current Gold Price per Gram.");
return;
}
// Calculation logic
// The karat is more for identification of the gold alloy, but the primary calculation
// for gold-filled items relies on the percentage specification (e.g., 1/20th = 5%).
// We'll use the goldPercentage directly for the calculation.
var goldWeightGrams = itemWeightGrams * (goldPercentage / 100);
var estimatedValue = goldWeightGrams * currentGoldPricePerGram;
// Display the result, formatted to two decimal places
resultValueElement.textContent = "$" + estimatedValue.toFixed(2);
}