Ruby factory in Fundão: Companhia Industrial de Materiais Duros
CIMD - Companhia Industrial de Materiais Duros
Cherries are not the only red product of Fundão; this town also makes rubies for more than 1,200 watch calibres. In the heart of Fundão we discovered a factory devoted to producing these watch rubies: CIMD, Companhia Industrial de Materiais Duros. Founded in 1990 as the outgrowth of a production unit of the company CHEVAL FRÈRES, CIMD has established itself as a world leader in the manufacture of watch jewels and technical components in hard materials. The watch on your wrist right now may well have rubies made in Fundão.
On our visit to CIMD we were warmly welcomed by its Managing Director of more than 30 years, Carlos Morgadinho, and by Marina Nascimento, Administrative Manager. We had the privilege of touring the factory and all its workshops. We also found a team entirely willing to answer any question, and premises in which the most traditional, manual knowledge and practices live side by side with modern CNC and laser machines.
The history of CIMD began in 1990, when CHEVAL FRÈRES set up its watch-jewel production unit in Portugal. Initially specialising in monocrystalline ruby, CIMD quickly expanded into other ultra-hard materials such as ceramics, sapphire and polycrystalline ruby. Today the company has a fully integrated workshop and recognised technical experts. It now has 34 years of activity and 140 employees.
What CIMD produces
Production currently consists of pierced jewels, with flat or domed faces and a straight or oval hole; cup jewels with a hole, a flat face and a straight hole; and cap jewels (end stones), with a flat or domed face and no hole. They are also able to make bottoms, rims and cabochons (the small stones on the crowns of some Cartier watches, for example).
Of the 140 employees, many are specialists who carry out work such as machining, drilling, turning and fine polishing. Some of the most specialised work is done in the sizing and calibration section.
CIMD, in Fundão, is today a world reference in the manufacture of synthetic rubies.
How rubies are produced at CIMD
Although aluminium oxide itself is not currently produced in Portugal, the entire process of machining, finishing and inspecting the rubies takes place in Fundão.
Here are some aspects of the transformation of alumina "pears" into watch rubies
Raw material
Al₂O₃, aluminium oxide, also known as alumina, arrives in the form of a pear or a red stone and is sliced down to a size very close to the final dimension, thus taking the form of a disc.
Machining
The shape and cut of the rubies are achieved using a variety of machines, from those in the photo below, already a few decades old, through CNC machines to powerful laser machines.
Polishing
In the tanks in the following photos, the flat surfaces of the rubies are polished to achieve the required geometry; this process meets tolerances of up to ± 5 μm. At the end, mirror-polished surfaces can be achieved.
After each ruby has been placed by hand on filaments, hot tin is poured over the filaments. This process ensures that the rubies hold their position, making the subsequent polishing stage easier.
Measurement and inspection
In a dedicated department the rubies are measured with the help of specialised tools such as micrometers. This measurement is done by sampling, for quality control.
We thank CIMD for the kindness and helpfulness with which the IPR was received, as well as for its excellent contribution to our knowledge of this precious aspect of watchmaking!
RUBIES IN WATCHMAKING
- TWO HISTORICAL FIGURES -
Nicolas Fatio de Duillier
Inventor of the first method for making jewels
for watches
Nicolas Fatio de Duillier, born on 16 February 1664 and died on 10 May 1753, was a mathematician, natural philosopher, astronomer, inventor and religious activist. Born in Basel, Switzerland, Fatio grew up mainly in the Republic of Geneva, of which he was a citizen, before spending much of his adult life in England and Holland. He is known for his collaboration with Giovanni Domenico Cassini on the correct explanation of the astronomical phenomenon of zodiacal light, for inventing the "push" or "shadow" theory of gravitation, for his close association with Christiaan Huygens and Isaac Newton, and for his role in the Leibniz–Newton calculus controversy.
It was Nicolas Fatio de Duillier who developed the first method for making jewels for mechanical watches.
Elected a Fellow of the Royal Society of London at the age of 24, Fatio never attained the position and reputation that his early achievements and connections promised.
In the 1690s he discovered a method of drilling a small, well-rounded hole in a ruby using a diamond drill.
Fatio tried, without success, to interest Parisian watchmakers in his invention. Back in London, he joined forces with the Huguenot brothers Peter and Jacob Debaufre, who kept a successful watchmaking shop in Church Street, Soho. In 1704 Fatio and the Debaufres obtained a fourteen-year patent for the exclusive use, in England, of Fatio's ruby-related invention.
In March 1705 Fatio showed the Royal Society samples of watches jewelled in this way. Isaac Newton's correspondence shows that in 1717 Fatio agreed to make a watch for Richard Bentley in return for a payment of £15, and that in 1724 he sought Newton's permission to use his name in advertising his jewelled watches. Fatio's method of drilling rubies remained a speciality of English watchmaking until it was adopted on the Continent in 1768 by Ferdinand Berthoud.
Auguste Victor Louis Verneuil
Creator of the process for producing artificial corundum
Auguste Victor Louis Verneuil was a French chemist renowned for inventing the first commercially viable process for manufacturing synthetic gemstones.
In 1902 he discovered the "flame fusion" process, later called the "Verneuil process", an economical method of producing artificial corundum, that is, rubies and sapphires.
Born in Dunkirk, France, in 1856, the son of a watchmaker-mechanic, Verneuil had a promising academic career; at 17 he became laboratory assistant to the chemist Edmond Frémy. He completed his first degree in 1875, his master's in 1880 and his doctorate in 1886. From 1892 he served as professor of applied chemistry in the organic chemistry section of the Natural History Museum in Paris for 13 years.
Verneuil devoted himself to many areas of chemistry, from the synthesis of ruby to the study of the phosphorescence of zinc blende and the chemistry of the rare-earth elements. He began his work on the synthesis of rubies by flame fusion as early as 1886, achieving significant results within six years. Although he deposited his sealed notes with the Paris Academy of Sciences in 1891 and 1892, he only announced his discovery in 1902. The Verneuil process is still used today as an economical way of producing artificial corundum, leaving a lasting legacy in the manufacture of synthetic gemstones.
- PHYSICAL AND CHEMICAL PROPERTIES OF RUBIES -
The rubies used in watchmaking are synthetic, and they are possibly the lowest-cost part in the whole watch. Even so, they have a series of properties that make them essential for a variety of industrial and scientific applications beyond watchmaking. Here are some of them:
Hardness
Synthetic rubies are exceptionally hard, with a rating of 9 on the Mohs scale of mineral hardness. This hardness is surpassed only by that of diamond, which makes synthetic rubies highly resistant to scratching and abrasion.
Chemical composition
Rubies are generally composed of aluminium oxide (Al₂O₃), also known as corundum. The presence of trace elements such as chromium, titanium and iron can give synthetic rubies different colours, ranging from red to pink and violet.
Transparency
Synthetic rubies are generally transparent or translucent, depending on their quality and on how they are cut and polished. High-quality ones can show excellent clarity and transparency, letting light pass through with minimal distortion.
Optical properties
Ruby has favourable optical properties, including a high refractive index and birefringence (an optical property of a material that has different refractive indices for different directions of light propagation). These properties contribute to its brilliance and sparkle when correctly cut and faceted.
Thermal stability
Synthetic rubies have good thermal stability and can withstand high temperatures without significant changes in their physical or optical properties. This property makes them suitable for use in high-temperature applications, such as laser technology.
Electrical insulation
They are insulating materials, which means that they do not conduct electricity.
This property makes them useful for applications that require electrical insulation, such as certain electronic and mechanical devices. Overall, the combination of hardness, colour, transparency, optical properties and thermal stability makes this material valuable for a wide range of industrial, scientific and decorative applications.
- TYPES OF RUBIES IN WATCHES -
Rubies in watchmaking can be of three types:
Pierced jewels
Cap jewels
Pallet stones
Impulse pin
- THE PROBLEM AND THE SOLUTION -
The problem: friction
It is possible to make fire by rubbing 2 pieces of wood together. This happens because of friction. As surfaces in contact move relative to one another, the friction between them turns kinetic energy into thermal energy, that is, it converts motion into heat.
Friction is the tangential resisting force that acts between surfaces in contact when there is relative motion, or an attempt at relative motion, between them.
This force results from the electromagnetic interactions between the atoms and molecules on the irregular surfaces in contact. Friction can be divided into dry, fluid or lubricated. Dry friction can be divided into static, when it acts to prevent motion from starting, and kinetic, when it occurs during motion. In addition, friction plays a crucial role in dissipating mechanical energy as heat, as mentioned in the previous example, directly influencing the wear of materials and the efficiency of mechanical devices.
Friction is not only a force that hinders motion; it is also essential to many operations and functions.
For example, without friction we would not be able to walk or hold objects.
However, friction also contributes to the wear of materials and can lead to a loss of energy efficiency in watch movements, owing to the conversion of mechanical energy into heat, as well as to the wear of parts. This is what happens with many wall clocks, which usually have no rubies, and with some wristwatches: the holes in the bridges and the mainplate become oval because of the action of the pivots.
To reduce friction, lubricants are applied in the right dose to the contact surfaces.
The solution: synthetic ruby and lubrication
Rubies are widely used in watches because of their exceptional physical and chemical properties. Here are the main advantages of this synthetic material:
Low friction: Rubies are extremely hard, surpassed only by diamond on the Mohs hardness scale. This hardness, combined with good lubrication, allows the parts of a watch to slide over one another with very little friction. Less friction means less wear and a longer service life for the watch.
Wear resistance: Because of their hardness, rubies resist wear even after years of continuous use. This is particularly important for the pivots and the areas they come into contact with, where the constant movement of the parts can quickly lead to wear.
Chemical stability: Rubies are chemically inert, which means that they do not react with substances that may get into the watch mechanism, such as water, sweat or dust.
Thermal resistance: Rubies have excellent resistance to changes in temperature, maintaining their performance even in extreme conditions. This is crucial for the precision of the watch, since variations in temperature can cause the watch's parts to expand or contract.
Improved precision: By reducing friction and wear at the critical points of the watch movement, rubies contribute significantly to the watch's precision over time. Less friction also means less variation in the energy needed by the watch movement, resulting in a more even distribution of energy.
Aesthetic and traditional value: Besides their functional advantages, the use of rubies in a watch movement introduces an aesthetic element. Traditionally, the number of rubies incorporated in a watch movement is seen as an indicator of its complexity and quality.
Synthetic ruby production processes
Synthetic rubies are made by a number of methods, each inducing the formation of crystals with specific properties, such as hue, transparency and degree of purity. The main processes used to synthesise rubies include:
1. Verneuil method (flame fusion)
Simplified diagram of the process sketch of an old furnace used
Simplified diagram of the Verneuil process and a sketch of an old furnace used by Verneuil to synthesise rubies by the Verneuil process.
Developed by Auguste Verneuil, as mentioned, at the end of the 19th century, this method is one of the oldest and most widespread approaches to producing synthetic rubies. The technique involves passing aluminium oxide powder (Al₂O₃) through a flame that reaches temperatures of about 2000°C, causing the powder to melt. This in turn is deposited on a substrate, gradually solidifying into a crystalline structure. The successive build-up of material results in the formation of a crystalline cylinder called a "boule", which is later cut into gems. Colourants can be added to the process in order to adjust the hue of the synthesised rubies.
2. Czochralski method
This method is recognised for producing high-quality synthetic crystals, including rubies. It begins with the immersion of a small seed crystal above a crucible containing aluminium oxide in liquid form. The seed crystal is carefully raised and rotated at the same time, enabling the crystal to grow from the melt. This technique is particularly valued for its ability to control the size and orientation of the crystal formed, resulting in gems of exceptional purity.
3. Hydrothermal method
This process mimics the natural genesis of gems, dissolving nutrients (namely aluminium oxide and colour-giving elements) in an aqueous solution subjected to high temperatures and pressures inside an autoclave. As the solution cools, the dissolved material begins to crystallise, adhering to a substrate or seed crystal and gradually growing in size. This method is notable for its ability to replicate the natural conditions of gem formation, allowing synthetic rubies to be produced with chemical and physical characteristics very close to those of their natural counterparts.
How to make synthetic rubies at home?
It is certainly not the most common hobby, but several enthusiasts have made videos on how to create synthetic rubies at home; here are a few:
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