Gold is a rare and noble precious metal, known since antiquity for its beauty, malleability, and durability. It is a chemical element identified by the symbol Au, derived from the Latin word aurum, meaning "shining".
Physically, it is distinguished by its intense yellow colour and characteristic shine, as well as being heavy to the touch, due to its density (19.3 g/cm³). Gold does not oxidise or rust, keeping its natural shine over generations.
It is resistant to air, humidity, and most chemical products, making it one of the most stable and long-lasting metals on the planet.
It only reacts under very specific conditions, such as contact with aqua regia (a mixture of strong acids) or potassium cyanide, laboratory processes used in the refining industry.
These properties make gold a metal of high economic value, widely used in jewellery, investments, electronics, and even medicine.
Gold is a rare and noble precious metal, known since Antiquity for its beauty, malleability and durability. It is a chemical element identified by the symbol Au, derived from the Latin word aurum, meaning "the shining one."
Physically, it is distinguished by its intense yellow colour and characteristic lustre, as well as its notable weight to the touch, owing to its high density (19.3 g/cm³). Gold does not oxidise or rust, preserving its natural brilliance across generations.
It is resistant to air, moisture and the vast majority of chemical products, making it one of the most stable and enduring metals on earth. It reacts only under very specific conditions — such as contact with aqua regia (a mixture of strong acids) or potassium cyanide — processes used in laboratory and refining industry settings.
These properties make gold a metal of significant economic value, widely used in jewellery, investment, electronics and even medicine.
In Portugal, the term "ouro de lei" refers to gold whose purity is legally recognised and certified by the Imprensa Nacional – Casa da Moeda (INCM).
Jewellery is made from metal alloys (gold mixed with other metals such as copper, silver, or palladium) to increase strength and adjust tone.
The degree of purity is indicated through the fineness (also referred to as the per mille content) — which represents the amount of pure gold present in a thousand parts of the alloy.
For example, the most traditional Portuguese "ouro de lei" is 800 thousandths (19.2 karats), meaning 80% of the alloy is pure gold and the remaining 20% corresponds to other metals.
Each legally sold piece carries two mandatory marks:
"Ouro de lei" doesn't just mean it's real gold, but rather that it complies with Portuguese law and has been certified by Casa da Moeda.
Portuguese gold is recognised worldwide for its high quality and purity. The most traditional fineness in Portugal is 19.2 karats (800‰), also known as "Portuguese gold".
However, national legislation allows for the production and sale of items with different finenesses:
19.2kt Portuguese gold is so distinctive that it is often referred to internationally as one of the most prestigious types of gold, due to its warm tone and the perfect balance between purity and durability.
Karat (kt) indicates the purity level of gold, not its weight. Pure gold is considered 24 karats (24 parts of gold in 24 parts of alloy).
As pure gold is too malleable, it is mixed with other metals (silver, copper, palladium, etc.) to achieve greater strength and rigidity.
This rule applies to any and all gold pieces. The more karats it has, besides being more valuable and expensive, the more durable it will be in terms of maintaining its original shine and colour. Gold jewellery pieces feature the following hallmarks:
Gold bars correspond to 24kt (karats) or 999‰ (thousandths) gold, that is, gold not alloyed with other metals.
Less common, but also permitted under Portuguese law, is 22kt (karats) or 916‰ gold, which corresponds to a minimum of 91.6% gold, with the remainder being other metals constituting the alloy.
"Not all that glitters is gold," as the saying goes — and it's true.
Distinguishing real gold from imitations requires careful observation and, ideally, professional appraisal. Even so, there are a few signs and tests that can help identify authenticity:
1. Look for hallmarks
Check whether the piece has symbols stamped with the fineness (e.g., 375, 585, 750, 800, 916, 999). These numbers indicate the gold content and are usually accompanied by the INCM mark. Antique pieces may have a worn hallmark — this does not mean they are not genuine.
2. Magnet test
Gold is non-magnetic, so it should not be attracted to a magnet. If the piece is pulled strongly, it is not real gold. However, the absence of a reaction is not definitive proof, as there are non-magnetic metals used in counterfeit pieces.
3. Density test
Gold is one of the densest metals in the world (around 19.3 g/ml). A gold piece will feel heavier than a fake piece of the same size. This test requires a precision scale and a volume measuring device, so it is usually carried out by professional appraisers.
4. Ceramic test
When the piece is rubbed on an unglazed ceramic plate:
⚠️ This method can scratch the piece — not recommended for jewellery of sentimental value.
5. Nitric acid test
Real gold does not react to nitric acid, while fake metals oxidise and change colour. This test is carried out in a controlled environment by qualified professionals, as the acid is highly corrosive.
6. Professional appraisal
The safest and most accurate way is to take the piece to official appraisers certified by Casa da Moeda. At Loja do Ouro and Gold Store Premium, we offer free appraisals carried out by licensed experts, using appropriate analysis instruments and chemical testing.
Weight, density, colour and hallmark all help identify gold, but only a certified appraiser can confirm its authenticity with complete certainty.
The value of gold is determined by its international spot price, which fluctuates daily in line with financial markets. The global benchmark is set by the London Bullion Market Association (LBMA), where the gold price is fixed twice daily — in the morning and afternoon — in US dollars per troy ounce (31.103 g).
The value of gold is determined by its international quotation, which fluctuates daily according to the financial markets.
The global reference is the London Bullion Market Association (LBMA), where the price of gold is fixed twice a day — in the morning and afternoon — in US dollars per troy ounce (31.103 g).
In Portugal, the price is converted into euros per gram and adjusted according to:
You can check the daily gold price table here.
The value of gold is determined by its international quotation, which fluctuates daily according to the financial markets.
The global reference is the London Bullion Market Association (LBMA), where the price of gold is fixed twice a day — in the morning and afternoon — in US dollars per troy ounce (31.103 g).
In Portugal, the price is converted into euros per gram and adjusted according to:
You can check the daily gold price table here.
The value of a gold bar (ingot) depends on three factors:
Gold Bars are currently among the most attractive investment products, both due to the rapid and growing rise in their price on international stock markets, and due to how easily they can be converted into financial liquidity.
Each bar has a unique serial number, the refiner's logo, and a purity seal, guaranteeing authenticity.
You can check the daily gold price table here.
If you're planning to sell some used gold pieces, the big question is always how much they're worth. Gold prices tend to rise when the economy is stagnant or when there are concerns about inflation. Whether it's gold rings, gold earrings, necklaces or gold chains, selling the used gold you no longer wear is an easy way to earn some extra euros.
First, you need to know the purity level of the used gold — whether it's 9kt, 14kt, 18kt, 19.2kt, 22kt or 24kt. The piece also needs to be examined for its hallmarks. If there is some wear on the gold, the value drops, and if it's simply a gold-plated piece, it's not even worth trying to sell.
The factors that influence the appraisal of a used gold piece are:
Gold Sovereigns, known internationally as Gold Sovereigns, are British coins minted since the early 19th century. It is the oldest currency in the world still in circulation.
In addition to their intrinsic gold value, many also hold numismatic value, i.e., collector's value.
The value of each sovereign depends on:
Sovereigns with the royal coat of arms on the reverse are generally more valuable than those depicting Saint George, especially in commemorative versions.
The condition of the coins is very important. If the effigy or the edges are damaged, even slightly, the coin may lose part of its value. However, it will never be worth less than the value of its gold content.
The best place to sell gold is always one that inspires trust and guarantees transparency.
Loja do Ouro and Gold Store Premium is a company licensed by Imprensa Nacional – Casa da Moeda (INCM), and strictly follows the legal rules for the appraisal and purchase of precious metals.
At our network of stores:
We buy and sell gold with ethics, transparency, and security, guaranteeing the best market price and a personalised service.
Yes. Gold is considered one of the safest investments in the world.
Unlike fiat currencies or shares, gold retains its value over time and protects against inflation and economic crises.
Main advantages:
For this reason, it is common for investors to hold part of their assets in physical gold — bars, coins, or high-fineness jewellery.
Gold is resistant to oxidation and does not rust or tarnish in water. However, frequent contact with chemical products, chlorine, perfume and cosmetics should be avoided. These agents can:
Recommendation: remove your jewellery before showering, entering a swimming pool or going into the sea — not only to preserve the longevity and original brilliance of your pieces, but also to avoid losing them in the water.
Pure gold does not oxidise, but the metals that make up the alloy (such as copper or silver) can react with chlorine, sweat, creams, or cosmetics, altering the surface tone of the piece.
This is natural and reversible.
To restore the shine:
At Loja do Ouro and Gold Store Premium, we offer professional cleaning, polishing, and restoration services for pieces.
NOTE: This service is not available on the spot in-store; it is carried out at our headquarters, but you simply need to visit one of our stores so the service can be quoted and the piece sent for repair.
Learn how to care for your gold jewellery in a simple and safe way:
1. At-home cleaning
Mix a few drops of mild liquid soap into warm water. Soak the jewellery for 15 minutes, then gently brush with a soft toothbrush. Rinse in clean water and dry with a cotton cloth.
2. Pieces with gemstones
Avoid soaking — clean with a damp cloth to avoid damaging the glue or the setting.
3. Avoid harsh products
Don't use toothpaste, bleach, or chemical products — they can scratch the piece and alter its shine.
For a deeper clean or maintenance, bring your pieces to Loja do Ouro and Gold Store Premium, where we can re-polish, tighten prongs, and restore the original shine.
