THE SHORT ANSWER
Purity changed in 2013; one-ounce fine-gold content did not
Standard one-ounce Gold Britannias dated 1987-2012 were struck in 22-carat, 916.67-fine gold. From 2013 the standard bullion coin moved to 24-carat, 999.9-fine gold. Both product records state one fine troy ounce of gold. The difference is the alloy and resulting gross composition—not extra gold in the newer coin.
One fine ounce plus alloy.
One fine ounce in four-nines gold.
For the standard one-ounce comparison.
Purity alone cannot pick the winner.
ERA COMPARISON
Use year-specific facts before using a scale or calculator
| Measure | 1987-2012 reference | 2026 current issue |
|---|---|---|
| Gold purity | 91.667% / 916.67 | 99.99% / 999.9 |
| Fine gold | 1 troy oz | 1 troy oz |
| Gross composition | Gold plus non-gold alloy | 31.21 g published gross weight |
| Diameter | Verify the exact dated product record | 32.69 mm |
| Denomination | £100 | £100 |
| Modern four-feature design | No | Yes for 2021-onward standard bullion |
The comparison deliberately does not publish one universal older gross-weight number. Alloy composition and product details should be taken from a record for the exact year and finish. This prevents a rounded contemporary figure from becoming a false counterfeit test for a historic issue.
THE MATH
One fine ounce is not the same as one ounce gross
Fine-gold content equals gross weight multiplied by fineness after units are aligned. A 22-carat coin needs more total mass to contain one fine ounce because 8.33% of the alloy is not gold. A 999.9-fine coin is much closer to the fine-gold mass, but its published gross weight still belongs to the exact product.
Use fineness as a decimal, such as 0.91667.
Both standard one-ounce eras start from one fine ounce.
Purity does not reveal the actual transaction markup.
A same-time exit quote can reverse the purchase choice.
Never discount a genuine 22-carat one-ounce Britannia as “missing” gold merely because it is not four-nines fine. The stated fine ounce is distributed within a heavier alloyed coin.
DURABILITY AND HANDLING
Alloy hardness is a physical trade-off, not free investment return
Alloy can make a coin more resistant to ordinary marks than a higher-purity product, while four-nines gold satisfies buyers who explicitly prefer 24-carat bullion. Neither preference changes the standard one-ounce fine-gold statement. Condition and dealer policy determine whether handling marks affect the bid.
A random-year pre-owned coin may trade closer to melt.
Some buyers value four-nines gold and modern security.
Choose the product that fits storage and acceptance.
Do not apply either standard specification to an unidentified coin.
SECURITY ERA
Purity year and security-feature year are separate boundaries
The move to 999.9 fineness occurred in 2013. The four enhanced visual security features arrived later, in 2021. A 2018 Britannia can therefore be a genuine 24-carat coin without the modern latent image and animated-wave field. Do not collapse those two dates into one authenticity rule.
One-ounce £100 Gold Britannia introduced in 22-carat gold.
Standard gold bullion moves to 24 carat / 999.9 fineness.
Four advanced visual features enter the bullion design.
King Charles III appears on the obverse; reverse remains product-specific.
The Britannia security-feature guide explains how to inspect the current design without treating a visual match as proof.
BUYING WORKFLOW
Compare a pre-owned 22K coin with a current 24K coin fairly
- Record exact year, denomination, size, finish, obverse portrait and packaging.
- Verify fine-gold content, fineness, gross weight and diameter from the dated official record.
- Capture dealer asks at the same time and with the same payment and delivery assumptions.
- Ask whether “best value” means random year, mixed condition or dealer-selected stock.
- Request executable buyback bids for each exact category and record inspection requirements.
- Compare all-in cost per fine ounce and immediate round-trip loss, not face value or purity alone.
A current 24K Britannia can be easier to inspect yet still be the worse economic purchase if its additional premium disappears at resale. A lower-premium 22K coin can also lose if a local dealer applies a larger condition or verification discount.
TAX AND VALUE BOUNDARY
Purity is only one part of investment-gold classification
UK investment-gold rules do not say that every 24-carat coin is automatically VAT-exempt or that every 22-carat coin is taxable. HMRC's coin definition includes a minimum fineness, mint-date, legal-tender and normal selling-price framework, alongside its published list. Both 916.67 and 999.9 exceed the stated 900 thousandths purity threshold, but the exact product and supply still matter.
HMRC's Capital Gains Manual separately identifies Britannia gold coins as sterling currency for the cited rule. Keep VAT classification, owner-level CGT, bullion melt value and collector value as four distinct questions.
METHOD AND LIMITS
Why the comparison avoids false precision
- Uses Royal Mint records for the 1987 introduction, 2013 purity change and current product.
- Compares the standard one-ounce product, not every proof, fractional or special issue.
- Does not invent a single older gross weight when the exact year should be verified.
- Separates fine-gold content from gross mass, purity, denomination and retail premium.
- Does not claim one era always receives a stronger bid or lower premium.
- Dates tax and security boundaries so they can be rechecked when official guidance changes.
PRIMARY SOURCES
Royal Mint and HMRC evidence
- Royal Mint one-ounce Britannia history for the 1987 22-carat introduction and 2013 move to 24 carat.
- Royal Mint pre-2013 22-carat Britannia record for 916.67 fineness, £100 denomination and one-troy-ounce pure metal content.
- Royal Mint 2026 one-ounce Gold Britannia for the current four-nines specification and design evidence.
- HMRC investment gold coin notice and HMRC Capital Gains Manual for the legal boundaries discussed.
FREQUENTLY ASKED QUESTIONS
22K and 24K Britannia questions
Which years are 22-carat Gold Britannias?
The Royal Mint says the Gold Britannia was introduced in 22-carat gold in 1987 and changed to 24-carat gold in 2013. Use the exact product record for unusual finishes, sizes or special issues.
Does a 24K Britannia contain more gold than a 22K Britannia?
Not when comparing the standard one-ounce versions. Royal Mint records state one troy ounce of pure gold for both the pre-2013 22-carat reference product and the current one-ounce 999.9-fine coin. The alloy changes gross composition, not the stated fine-gold unit.
Why is a 22K one-ounce Britannia heavier?
A 22-carat coin needs additional non-gold alloy to contain one fine ounce of gold. Gross weight therefore exceeds the pure-gold weight. Use year-specific official mass rather than the current 31.21-gram specification.
Is 22K or 24K better for investment?
Neither purity is permanently better. The defensible comparison uses the exact coin, all-in price, condition, verification and same-time buyback bid. A lower-priced 22K coin can win if the exit bid remains strong; a current 24K coin can win when security and acceptance justify the premium.
Do pre-2013 Britannias have the four modern security features?
No. The enhanced latent image, surface animation, micro-text and tincture-line system was introduced later. Do not reject an older coin for lacking a feature that did not belong to its issue.
Are both 22K and 24K Britannias UK legal tender?
The Royal Mint identifies the one-ounce Britannia denomination as £100 and describes pre-2013 22-carat Britannias as UK bullion coins. Confirm the exact issue and current HMRC guidance rather than applying a blanket rule to every similarly named product.