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What's New: Hallmark Decoder, 6 More Coins & 7-Day Sparklines Are Now Live

Three updates just shipped on the Currency, Crypto & Gold Calculator: a built-in hallmark/purity stamp decoder, six additional cryptocurrencies, and inline 7-day sparkline trend charts. All three are live on the tool right now — no reload trick, no hidden setting. Here's exactly what changed and how to use each one.

In this guide

New: hallmark / purity stamp decoder

What shippedA dedicated Hallmark / purity stamp decoder tool now lives on the Gold & Silver tab, next to the value-by-weight and troy-ounce converters — pick a stamp from a dropdown and it decodes the purity instantly, no separate lookup chart needed.

If you've ever flipped over a ring or clasp and found a three-digit number instead of a "14K" mark, you already know the friction: you either recognize the number from memory or you go searching for a conversion chart. This tool now handles that step directly. Open the Gold & Silver tab, scroll past the spot-price fields to the tools grid, and find the card labeled "Hallmark / purity stamp decoder."

Example walkthrough: say a bracelet is stamped "916." Select 916 from the stamp dropdown and click Decode stamp — it maps that mark to its purity fraction and closest karat equivalent right away. From there you'd move to the "Value by weight" tool next to it, pick the matching karat, enter the bracelet's weight, and get a dollar figure from whatever gold spot price you've entered at the top of the tab. The decoder and the value calculator are separate tools that hand off to each other, so decoding a stamp is now a one-click step instead of a manual lookup.

Common stamps the decoder recognizes — for reference
StampPurityKarat
3750.3759K
5850.58514K
7500.75018K
9160.91622K
9250.925Sterling silver
9990.99924K
Good to know: the decoder also covers the common silver mark 925 (sterling), so the same tool works whether the item stamped in front of you is gold or silver — you're not limited to gold-only karat numbers.

New: six more cryptocurrencies

What shippedXRP, Cardano (ADA), BNB, Tether (USDT), USD Coin (USDC), and Litecoin (LTC) have been added to the live price table on the Crypto tab, bringing coverage from 4 coins up to 10 — all fetched live from CoinGecko alongside the original Bitcoin, Ethereum, Solana, and Dogecoin.

Open the Crypto tab and the price table now lists all 10 coins with their live US-dollar price and 24-hour change. The coin dropdowns in the "Crypto value calculator" and "Crypto converter" tools below the table have grown to match, so you can convert any of the 10 coins into USD or into each other — for example, checking how much USDT a given amount of XRP converts to, without leaving the page.

The two stablecoins in the new lineup, USDT and USDC, are worth calling out specifically: unlike Bitcoin or Litecoin, they're designed to hold a value close to one US dollar rather than fluctuate with the market. Having them in the same live table as the more volatile coins means you can sanity-check a stablecoin balance in the same glance as checking Bitcoin's price, instead of assuming it's exactly $1.00 and moving on.

New: 7-day inline sparklines

What shippedBoth the popular currency-pair cards and the crypto price table now show a small inline 7-day sparkline — a compact line chart that traces the last week's movement without opening a separate charting page.

On the Currency tab, the row of popular USD exchange-rate cards near the top each now render a thin sparkline under the price, giving you a sense of whether that pair has been climbing, falling, or flat over the past week. On the Crypto tab, the live price table has a new "7-day trend" column, sitting right next to each coin's price and 24-hour change, showing the same kind of at-a-glance shape for the top coins.

Why it's useful in practice: a 24-hour change figure alone can be misleading — a coin up 3% today might have been down 15% over the rest of the week, or a currency pair showing a flat daily change might have been trending steadily in one direction for days. The sparkline doesn't replace the price or the percentage change, it just adds the shape of the last seven days next to the number you're already looking at, so you're not reading a single data point in isolation.

Good to know: the sparklines are drawn from the same live data source already powering the price and 24-hour change figures — there's no separate feed to load, and refreshing the tab refreshes the trend line along with everything else.

Try the hallmark decoder, the 10-coin crypto table, and the new sparklines — free, no sign-up.

Open the Currency, Crypto & Gold Calculator →

Frequently asked questions

How do I use the new hallmark stamp decoder?
Open the Gold & Silver tab, scroll to the Hallmark / purity stamp decoder tool, and pick the stamp printed on your item (585, 750, 916, 925, 999, and other common marks) from the dropdown. Click Decode stamp and it shows the matching purity fraction and karat equivalent instantly, without needing you to look up a conversion chart separately.
Which six cryptocurrencies were just added?
XRP, Cardano (ADA), BNB, Tether (USDT), USD Coin (USDC), and Litecoin (LTC) were added alongside the existing Bitcoin, Ethereum, Solana, and Dogecoin, bringing the total to 10 coins with live prices, 24-hour change, and a converter that works coin-to-coin or coin-to-USD.
Where do I see the new 7-day sparkline?
On the Currency tab, the popular USD exchange-rate cards each show a small inline sparkline under the price. On the Crypto tab, the live price table has a dedicated 7-day trend column next to each coin's price and 24-hour change. Both are drawn directly from the live data already being fetched, so no extra setup or click is needed.
Do these new features change how the gold and silver spot-price math works?
No. Gold and silver value calculations are unchanged: weight in grams x (spot price / 31.1035) x purity fraction, using the spot price you enter yourself. The hallmark decoder is a lookup convenience that sits next to that math, not a replacement for it — after decoding a stamp you'd still use the value-by-weight tool with the matching purity to get a dollar figure.
Are the new coins and sparklines live data or estimates?
The six new coins are fetched live from CoinGecko's public market-data API, the same source used for the original four coins, so their prices and 24-hour change are current at the time you load the page. The 7-day sparklines are built from that same live historical data, refreshed whenever you open or refresh the relevant tab.

Related guides

Methodology note: currency figures use live rates from Frankfurter (ECB reference rates) and crypto prices from CoinGecko's public API, both fetched at the time of viewing. Feature availability described here was verified against the current version of the tool as of this article's publish date. This article is for informational purposes only and is not financial advice.