How to Mint Gold Coins According to Modern Mint Instructions

Gold coins have served as a symbol of wealth and a reliable tool for capital preservation for centuries. Today, interest in them is only growing: investors are actively acquiring assets such as the famous "George the Victorious" or the historical "Siyatel" червонец. But have you ever wondered what complex journey pure gold undergoes before transforming into a shining investment masterpiece?

A modern mint is a high-tech enterprise where age-old metallurgical traditions meet precision engineering. The process has evolved from ancient manual forging to automated hydraulic presses and laser engraving of dies at Gosznak.

In this practical guide, we will detail every stage of production: from calculating the alloy mass and blanking the coin blanks to applying the rim, final high-pressure striking in hundreds of tons, and combating technological defects.

Raw Material Preparation: Choosing Gold Purity and Creating the Alloy

The birth of any gold coin begins not in the striking press, but in the mint's melting shop. Pure gold is extremely soft on its own: a coin made of pure metal can be easily scratched by a fingernail or deformed if it falls accidentally. To give the product the necessary mechanical strength, wear resistance, and durability, an alloy is added to the precious metal—other metals, most often copper or silver.

The correct selection of the alloy composition and the precise adherence to proportions is the foundation that determines not only the physical properties of the future coin but also its investment appeal. In modern high-tech production facilities, such as Gosznak, this stage is controlled to the accuracy of hundredths of a gram, because the slightest error during raw material preparation will make high-quality striking of a complex relief impossible.

What Gold Purity is Used for Modern Investment Coins

In modern numismatics, the choice of gold purity for investment coins depends on the issuer's standards and technological requirements. Today, two main standards dominate the market:

• Pure Gold (Purity .999 or .9999): This is the international standard for most modern issues. A prime example is the Russian "George the Victorious." The mint uses metal of the highest purity to minimize the proportion of impurities. Such coins possess an impeccable luster but require extremely careful handling, as pure gold is very soft.
• Gold Alloys (Purity .900 or .917): A historical standard for strength. The alloy of gold with copper (the alloy) was used for the Soviet "Siyatel" червонец (900 purity) and is still used for the South African "Krugerrand" (917 purity). The addition of copper makes the coin wear-resistant, protecting the relief from abrasion.

Calculating Alloy Mass and Melting the Alloy at the Mint

To obtain an alloy of a specified purity, the mint's technology calculates the exact alloy mass. If the goal is to strike coins from an alloy (for example, the historical "Siyatel" червонец of 900 purity), copper is added to the pure gold as the alloy.

The alloy mass ($M_a$) is calculated using the formula:

$$M_a = M_g \times \frac{1000 - P}{P}$$

where $M_g$ is the mass of pure gold, and $P$ is the target purity. To obtain 1 kg of 900-purity alloy, it is necessary to combine 900 g of gold and 100 g of copper. When producing modern 999-purity coins, the calculation is aimed at minimizing impurities.

The alloy is melted in induction furnaces at a temperature of about 1100 °C. To prevent the oxidation of the alloy (especially copper) and the formation of micropores, the process is conducted in graphite crucibles under a protective layer of flux or in an inert gas environment (argon). The homogeneous melt is poured into molds to obtain strip blanks.

Manufacturing Coin Blanks and Rim Processing

After the gold alloy of the required purity is successfully cast into strip ingots, the critically important stage of mechanical processing begins. At a modern mint, transforming a massive gold strip into a perfectly round, soft, and striking-ready blank is a high-precision engineering process. Any error at this stage, whether a thickness deviation of a micron or a microcrack in the metal, will inevitably lead to defects during the final press strike. This stage combines the plastic deformation of gold under colossal pressure from rolling mills, precision die cutting of discs, and their subsequent thermal and chemical preparation. Special attention is paid to forming the rim—the side surface of the future coin, which not only protects the product from counterfeiting but also sets its exact geometric parameters before feeding into the striking unit.

Rolling Gold Strips and Cutting Round Blanks

After the gold alloy is cast, the stage of plastic deformation begins at the modern mint. The ingots are fed into multi-roll rolling mills, where under colossal pressure, they are gradually transformed into thin gold strips. This process requires jeweler's precision: the strip thickness is continuously monitored by laser sensors with micron accuracy, because the slightest deviation will cause the weight of the finished investment coin to fall outside the strict standard.

The resulting gold strip is directed to a high-speed blanking press. Special punches, operating at several hundred strikes per minute, cut perfectly round coin blanks from the strip.

• Geometric Accuracy: At Gosznak, the blanking dies are manufactured with minimal tolerances to prevent the roundels from becoming oval.
• Recycling: The perforated strip remaining after blanking ("mesh") is immediately sent for remelting, ensuring a zero-waste cycle when working with pure gold.

During rolling, the metal is compacted and gains hardness (work hardening), so the blanks require thermal softening before further processing.

Cleaning, Thermal Annealing of Blanks, and Rim Application

After blanking, the gold discs undergo mandatory cleaning and degreasing in special ultrasonic baths to remove residual process lubricants.

The next crucial stage is thermal annealing. During rolling and blanking, the gold undergoes work hardening and loses plasticity. To restore softness to the metal, the blanks are heated in pass-through furnaces in a protective atmosphere (usually using a nitrogen-hydrogen mixture) at a temperature of about 600–650 °C. The protective atmosphere prevents the oxidation of the alloyed copper. After annealing, the discs are carefully cooled and washed in a weak acid solution (etching) to give them a perfect shine.

Preparation is completed by rimming on a rimming machine. The blank is rolled between a stationary plate and a rotating disc. This process solves two problems:

1. It forms a protective raised edge around the circumference.
2. It applies reeding or inscriptions to the side surface (the rim).

The diameter-calibrated blank is completely ready to be fed under the die.

After the gold blanks have undergone thermal treatment, cleaning, and rimming, they are completely ready for relief application. However, the quality of the final coin—whether it is the mass-produced "George the Victorious" or the collectible "Sower"—depends directly on the precision of the striking tool and the calibration of the equipment. At this stage, high-precision technologies for creating dies and the fine-tuning of hydraulic presses come into play.

A die is the "heart" of coin production, bearing the mirror image of the future obverse and reverse. The slightest error in its geometry or the force of the press strike can lead to defects in the expensive gold alloy. Therefore, the preparation of the tooling requires jeweler's precision, combining the traditional craftsmanship of Goznak engravers with advanced laser technologies.

Engraving and Laser Matting of Dies at Goznak

At the mints of JSC "Goznak," the creation of dies begins with the generation of a digital three-dimensional model of the future coin. Based on this file, precision CNC engraving machines cut the primary relief onto a blank made of high-strength tool steel.

To achieve flawless striking quality (especially proof and brilliant uncirculated standards), laser matting technology is employed:

• Laser micro-relief etching: Ultra-short pulses from a solid-state laser create microscopic roughness on specific areas of the die. Upon striking, this relief transfers a noble matte texture to the coin.
• Manual field polishing: Areas of the die intended to become the coin's mirror field are polished manually by masters using diamond pastes of varying grit.
• Application of protective elements: The laser allows for the engraving of hidden images, microtext, and diffraction gratings that change color under different angles.

After laser processing, the dies undergo heat treatment and chromium plating to increase their wear resistance before being installed in the press.

Preparation of Hydraulic Presses and Strike Force Adjustment

Following the preparation of the dies, the stage of setting up the striking equipment begins. Modern mints use high-tech hydraulic presses with capacities ranging from 80 to 300 tons, which ensure the perfect accuracy and repeatability of every strike.

Setting up the press for gold requires jeweler's precision due to the physical properties of the precious metal. Pure 999 fineness gold is extremely ductile, so excessive pressure can deform the blank or damage the die. Insufficient strike force will prevent the relief elements from being completely filled with metal.

The equipment preparation process includes key steps:

• Die pair centering — precise alignment of the upper and lower dies in the press to prevent image shifting.
• Pressure adjustment — programming PLC controllers for the optimal force (usually around 100–150 tons for standard 7.78-gram coins like "George the Victorious").
• Ejector calibration — adjusting the hydraulic cylinder for the careful removal of the finished product without damaging its rim.

For striking proof quality coins, the press is programmed to perform several sequential strikes, which guarantees flawless rendering of the complex relief.

Coin Striking Technology Process

Once the hydraulic presses are set up and the strike force is calibrated to the nearest kilogram, the most mesmerizing stage of production begins—the actual birth of the coin. At this moment, the prepared gold blank transforms into a genuine work of numismatic art under the influence of colossal pressure.

The modern striking technology process at leading mints, such as Goznak, is a highly precise automated cycle. Here, it is critically important to maintain a balance between the equipment's operating speed and the flawless quality of the finest relief details, which directly depends on the chosen striking mode and the intended purpose of the finished product.

Step-by-Step Relief Application Under Press Pressure

At a modern mint, the process of striking gold coins is automated and perfected. The prepared blank is fed into the working area of a high-speed hydraulic or mechanical press.

The relief transfer process occurs step-by-step:

1. Positioning: The blank is automatically centered in the printing ring, which rigidly fixes its diameter and prevents metal spreading.
2. Compression and Strike: The obverse and reverse dies close simultaneously. For striking investment coins made of pure gold (such as "George the Victorious" or the "Sower" gold coin), a pressure of 100 to 300 tons is applied at Goznak.
3. Plastic Deformation: Under colossal pressure, the gold instantly fills the finest elements of the die's laser engraving. Simultaneously, the metal is extruded to the sides, forming the finished rim in the clamping ring.
4. Extraction: The press releases, the lower die lifts, and the ejector cylinder carefully moves the finished product into the tray, preventing coin collision.

Differences in Striking Ordinary Investment and High-Quality Commemorative Coins

The technological process at the mint is strictly divided depending on the category of the product being issued.

Investment coins (uncirculated quality, such as "George the Victorious") are struck in automatic mode at high speeds. The blanks for the coins are fed to the press mechanically, and the die delivers a single strike. This ensures enormous productivity but allows for the appearance of microscopic scratches when finished products fall into the collection bin.

Commemorative coins (proof quality) require a jeweler's approach:

• Blank preparation: Each piece of pure gold is polished manually to a mirror shine.
• Special dies: Goznak uses dies with a mirror field and deeply matte laser-etched designs.
• Double strike: The hydraulic press performs two or more strikes on one blank at a reduced speed for perfect relief rendering.
• Contact exclusion: The mint operator transfers blanks and finished coins only by hand while wearing special gloves, preventing contact between the items.

Defect Control, Quality Inspection, and Packaging of Finished Products

After the hydraulic press has imparted the filigree relief onto the gold blank, the finished product proceeds to the final, yet most critical, stage of production—technical inspection. Even at advanced Gosznak mints, automation does not eliminate microscopic equipment failures or the influence of the external environment. At this stage, Quality Control (QC) specialists identify hidden defects, conduct high-precision measurements of physical parameters, and package the items for protection against external influences. Special attention in modern production is paid to analyzing specific defects that may appear on pure precious metal even during storage, as well as strictly adhering to weighing standards.

Why Rust Spots Appear on Gold Coins Like "George the Victorious"

The phenomenon of reddish and brown spots appearing on investment coins made of pure 999 fineness gold (such as "George the Victorious") has long been a subject of debate among investors. Physically pure gold is not susceptible to corrosion; however, the technological nuances of minting at the mint explain this anomaly.

The cause lies in microscopic contamination of the blank surface with iron during production:

• Wear of Steel Tools: High-strength dies and cutting stamps undergo colossal loads during operation. Microscopic particles of tool steel can detach and remain on the working surfaces.
• Metal Transfer During Striking: When the press strikes under hundreds of tons of pressure, these invisible iron particles are literally "pressed into" the soft, plastic structure of 999 fineness gold.
• Oxidation: Upon subsequent contact of the finished product with oxygen and moist air (even through micro-cracks in the plastic capsule), the embedded iron begins to rust, forming characteristic reddish spots.

Defect Cause	Mechanism of Occurrence	Minimization Method at Gosznak
Steel Microparticles	Embedding under press pressure	Ultrasonic cleaning of dies and blanks
Storage Condition Violation	Iron oxidation in a moist environment	Use of hermetic capsules

Modern Gosznak mints maintain strict control over equipment purity, including regular chemical treatment of dies. It should be noted that the presence of such spots does not reduce the actual value of the precious metal contained in the coin, although it does affect its aesthetic appearance.

Control Weighing, Defect Detection, and Encapsulation of Finished Products

After striking and cleaning, the finished coins are sent to the final quality control stage, where each piece undergoes the strictest inspection before leaving the mint.

Control Weighing
Each gold coin is weighed on precision analytical balances with accuracy to the thousandth of a gram. For investment coins, such as "George the Victorious" (pure gold weight 7.78 g), state standards allow only minimal positive deviations. Negative tolerance is strictly forbidden—the investor must receive exactly the amount of precious metal stated.

Visual Inspection and Defect Detection
Specialists from the Quality Control (QC) department examine the coins under microscopes and special magnifying lamps. At this stage, items with the following defects are rejected:

• Micro-cracks and scratches on the mirror field;
• Incomplete striking of relief elements or inscriptions;
• Rim defects (burrs, uneven thread spacing);
• Traces of oxidation or foreign microparticles.

Encapsulation
Since 999 fineness pure gold is extremely soft and sensitive to mechanical stress, the coins cannot be handled with bare hands. Immediately after defect detection, the items are placed in hermetic protective capsules made of chemically neutral plastic, either automatically or manually (wearing special lint-free gloves). For "proof" quality coins, this process takes place in dust-free boxes, guaranteeing the preservation of the mirror surface for decades.

Conclusion

Modern gold coin production is a high-tech symbiosis of metallurgy, precision engineering, and applied art. Having passed through the entire technological path—from calculating the alloy mass and smelting the alloy to precision striking on Gosznak's hydraulic presses—the precious metal is transformed into a reliable investment tool and a collectible object. Every stage, whether preparing blanks for coins, applying a complex rim, or laser matting dies, requires absolute precision and strict adherence to mint regulations.

A deep understanding of these processes allows numismatists and investors to approach the formation of their collections and portfolios consciously. Knowing how 999 fineness pure gold or the historical "Siyatel" alloy behaves under press pressure helps in correctly assessing the condition of coins and organizing their storage. It becomes clear now that even rare defects, such as the appearance of iron oxidation traces on "George the Victorious" investment coins, are due to subtle nuances of industrial production and do not reduce the real value of the precious metal contained within them.

Every gold coin leaving the mint walls in a protective capsule represents a masterpiece of engineering thought. In an era of rapid change, physical gold, struck according to strict state standards, remains an unshakable standard of reliability, uniting age-old traditions with the technologies of the future.