What is the purity difference between Yellow or K Gold? Explain the detection, calculation and judgment method of gold purity in detail! | JEWEL CAFÉ Malaysia

Date Updated: March 29, 2023

What is the purity difference between Yellow or K Gold? Explain the detection, calculation and judgment method of gold purity in detail! | JEWEL CAFÉ Malaysia


I just know that gold have different types of purity.


Yes, it is different for each gold types.


How to identify the gold purity?


Please continue to read.

Gold has received a lot of attention from all over the world which is also known as jewelry and assets since ages. Apart from the famous material, there are only some people who understand the difference and the meaning and purity of engraving.

The Value of Gold Depends on “PURITY”.

We will expose you to the knowledge the “purity” that determines the gold price standard from different angles, and you can learn how to check the purity of gold by yourself for your reference.

What is the meaning of “K” in “Koo”? About Gold Unit and Indications

Have you ever seen the “K24” or “K18” engraving as a gold mark on gold products? The “K” in “K○○” refers to the abbreviation of “karat”, and the so-called “K○○” symbol indicates the “gold purity” used in the product.


Gold content can refer as “gold purity”, the percentage of gold (pureness of gold) that contained in the product. Do you know that literally most of the gold products are not made of only “pure gold”. Thus, for jewelry and other gold ornaments they are made of pure gold with other metals different from “only pure gold” which it is made of “pure gold” without mixed with other metals.

The purity of gold is indicated at a rate of 24 points

To indicate the purity of gold, Japan uses a 24-point rate which it is 100% pure gold (pure gold) known as K24 (24 gold). In Japan, they refer 99.99% or higher purity gold is labeled as K24. Every time K1 is increased, the pure gold content will increase by 4.17%. If it is K18, the pure gold content will reach 75%.

Note 1 – The difference between “K Gold (karat)” and “Carat”

Do you aware that the spelling of “karat” and “carat” that can use for gems and gold are totally different, and their units is different too. The “karat” for gold means “purity”, while the “carat” of gems means “weight”. In Japan the purity of gold is expressed, and it will be marked as “18 gold” to avoid confusion with the “carat” used for gems.

Note 2 – About “24 points rate” and “1000 points rate”

Because the locust bean has 24 equal parts, it is said that the 24 equal parts were initially used as the unit of pure gold and were later determined to be the unit of gold trading. Another statement is that there are 24 hours in a day, and this unit is still in use today using a 24-point scale as the general unit. The idea of so-called 100 points emerged after humans first came into contact with gold. The more accurate 1000-point rate is used to denote the 100-point rate due to the development of the 100-point rate as well as the widespread use of the terms “Pt900” and “Silver925” for platinum and silver, respectively. K24 is designated as 999.9 points if gold is marked with 1000 points. This method is most commonly used for ingots (gold bars, bullions).

The intention of mixing gold with other metals

Higher purity results in more valuable and attractive appearance. But why are other metals blended into alloys when making jewelry? In actuality, the soft texture, heat resistance, deformation, and damage of pure gold are drawbacks. On the other hand, it can be turned into a mixed alloy because it has the property of being simple to blend with other metals. To compensate for pure gold’s shortcomings. It also has the benefit of allowing for the color of rose gold and platinum to be different by altering the type and proportion of the blended metal. Here, we’ll go over the ratios of pure gold to the most popular jewelry alloys, including gold (YG), rose gold (PG), and platinum (WG).

YG | when it’s K18 | (75.00: 15.00: 10.00%)
PG | when it’s K18 | (75.00: 10.00: 15.00%)
WG | when it’s K14 | (58.33: 41.67: 0.00%)

*The numbers in ( ) indicate the ratio of pure gold: pure silver: pure copper
*It is only a general value; the correct ratio will vary depending on the product

Incidentally, platinum, which is often confused with platinum, is an alloy of pure gold mixed with silver, nickel, and palladium. In fact, the two are completely different.

Will it vary by purity? Uses and characteristics

Most of the gold products circulating in the market are one of five types: K24, K22, K18, K14, and K10. The following will introduce the pure gold content ratio, characteristics and uses.

K24 ・ 24 GOLD ( PURE GOLD 99.99% ~100%)

The pure gold content will not decay or change color because it is nearly 100% and it luster will maintain forever. However, its soft texture absolutely not suitable for making jewelry and its mainly processed into products with asset value such as gold bar/ bullions or coins that is more solid. The gold leaf with the impression of pure gold is usually K23 containing 4.90% pure silver and 0.66% pure copper.

K22 ・ 22 GOLD ( PURE GOLD 91.7% : MIXTURE 8.3% )

This kind of purity is rarely made, but in recent years it has begun to attract attention, and its main use in making jewelry. Although it is harder than K24, it still has the characteristics of softness and easy damage due to its high gold content, so be careful when using it. In Asian countries outside of Japan, they preferred dark golden, so K22 jewelry with close to pure gold tone and brightness seems to be quite popular.

K18 ・ 18 GOLD ( PURE GOLD 75% : MIXTURE 25% )

K18 gold is very suitable for jewelry because it can maintain high purity and has easy processing softness and appropriate hardness. Even the color variations of rose gold and platinum are extremely attractive. In addition to jewelry, it is also used for a wide range of purposes such as watches, lighters, cameras, and smart phone cases.

K14・ 14 GOLD ( PURE GOLD 58.5% : MIXTURE 41.5% )

However, as the amount of pure gold decreases, the gloss will deteriorate and the chance of discoloration will rise, despite the fact that increased durability can be achieved by adjusting the proportion of the mixture. However, due to its low gold content and low price, it is processed into a variety of goods, including jewelry and writing instruments, and is widely used.

K10・ 10 GOLD ( PURE GOLD 42% : MIXTURE 58% )

K10 was introduced recently as a result of the rising cost of gold. The brightness is not as good as the previously mentioned pure products due to the mixture’s higher proportion of gold, and it has a propensity to rust. But because it is inexpensive and simple to process, it is widely available. The majority of them are used to create jewelry. People with sensitive skin are more likely to develop metal allergies as the purity of gold declines. When purchasing jewelry, it is best to choose items rated K18 or higher if allergies are a concern.

An easy way to check the purity of gold yourself

How can you check the purity of gold? If you are from operator industry, you can check by using professional X-ray analyzers for identification. Which this might quite expensive, and it is not easy for individuals to buy. Therefore, the most appropriate way is to entrust an expert to appraise.

In addition, the following context will introduce three simple methods that individuals can also measure the purity of gold (for your reference). Whether you want to actually try it or read it based on knowledge or curiosity, please make good use of this opportunity to learn about the identification method of gold purity.

STEP 1, Confirm the Weight & Texture – Firstly, Understand about the nature of gold

This method is not used to identify the gold purity, but to investigate “fake or real gold”. Firstly, I want to introduce on how to understand the nature of gold.
Check Method
Based on the characteristics of “gold being heavy, easy to heat and cold”, the judgment can be made only by touch using bare hand. The characteristic of high-purity gold products is that they are heavier than the size of their appearance. In addition, there is a cold feeling at the moment of touching, but due to the high thermal conductivity, it will be warmed by body temperature immediately.

• It takes experience to develop these feelings
• High-precision fake gold cannot be judged by this method

STEP 2, Submerged in water to measure specific gravity-an ancient method before the era

There is another method to check the purity of gold from the specific gravity by using the characteristic of “heavy gold”. This is a popular method used in the time of Archimedes before the Era. Specific gravity means that when the weight of water is 1, use the same volume (1cm3) as the object to express the weight. When water is 1, the specific gravity of K24 pure gold is 19.13-19.51 (approximately 20 times that of water); K18 is 14.84-16.12 (approximately 15 times that of water), which shows how heavy the weight of gold is. So, how is the specific gravity measured? Although it can be easily measured with a professional hydrometer, the price of a hydrometer is more than 100,000 yen, so I will explain how to easily measure specific gravity using a kitchen scale that can be purchased for thousands of yen. (Please use 0.1 gram as the unit of measurement, with the “zero function” that can deduct the weight of the container). Here will be an example of gold products engraved with K18.

Check Method
1. Firstly, measure the weight of the gold product under inspection (assume this value as A).
2. Next, place the container with water (a lighter weight container is preferred) on the electronic scale and use the “zero-return function” to display zero.
3. Then, put the gold product to be inspected into the water and measure the value (assuming this value as B). Water is 1cm3=1g, so the value of B becomes the volume of gold products.
4. B÷A=The proportion of the inspection object (assume this value as C).
The specific gravity of K18 is 14.84-16.12. As long as the C value is within this range, the possibility of belonging to K18 as indicated by the engraving is quite high.

This method should take note of the fact that at the aforementioned point 3, the gold product needs to be completely submerged in water and in a suspended state in order to serve as the measurement object. Leaning against the bottom or sides of the container is prohibited, in addition to being exposed to the water’s surface. As a result, a net need to be ready. If it’s a ring, it should be hung with wire. It must now be zeroed and shown as zero in the in-position state, regardless of whether the object is a container or piece of equipment that has been filled with water. But there are also drawbacks to this approach.

• It is impossible to measure products with special shapes such as a hollow center and no room for water intake, and design jewelry products.
• When using fake gold made of metal whose specific gravity is close to gold, such as “tungsten”, the measured value is almost the same as real gold.

STEP 3, Investigate using touchstones-an identification method passed down from the Edo period

The last thing I want to introduce is the method of using the touchstone, which has been used since the Edo period, and a very historical method of identification is to use the black slate of the so-called “Nachi Black Stone” as the touchstone.
Check Method
Examine the color, depth, and remaining condition of the scraped gold left on the stone’s surface after rubbing the examined gold product against the touchstone to ascertain its purity. As the purity of the gold decreases, the orange color changes into a bright hue, but when the gold is pure, it will exhibit a strong orange color that forms a deep dark shade close to bright yellow. The copper content will significantly increase, and the color will darken when it drops from K14 to K10 or so. However, unless you have a lot of experience, it is challenging to judge by color. It is advised to select a “test gold bar” that verifies the golden hue in accordance with purity as a point of comparison. A small touchstone can be bought for only a few thousand yen, and those who are interested can challenge it.

• It can be a destructive inspection, when the surface scratch and sometimes could damage the inspection object due to cutting.
• Novices can’t easily distinguish color by purity.


The value of gold depends on “purity”. Those who consider gold as an asset or buy gold jewelry, if they can really understand the purity knowledge, will be helpful when buying.


I find out more interesting facts in here.


Yes that's true, you can also get more information about other luxury item facts in here


Oh okay! Thank you so much.


You're welcome

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