Throughout history, trading remained one of the most important human interactions. Besides its economic aspects, trading goods also contribute to the expansion of cultures, religions, and many other concepts. It for sure speed up the development of human life, support the advancing of technology and shape the world which we live in today. In human history, there were two important trade goods which are used heavily. Yes, diamond and silk. Now, let’s look at them closer.
Diamond and silk are the most valuable commercial goods of the time period between ancient history and modern history. From Ancient Egypt and China to India and Anatolia, diamond and silk are the most common materials transported and traded. Diamond is a precious crystal of pure carbon that has been crystallized. It is used in jewelry making as well as industrial applications. On the other hand, silk is a natural fiber commonly produced by silkworms. Its usage area is generally the textile industry.
Diamond As a Commercial Good
In the process from the beginning of humanity to the present, the separate and combined use of precious metals and precious ornamental stones has been a tool that symbolizes the power and status of the people who use it. We can say that diamond is the most well-known and most valuable of these precious ornamental stones. The industrial value of diamonds is understood outside the jewelry sector, and today it has become an important material for many disciplines in the field of industry and production.
Crystal diamond, which is the most valuable and hardest of precious stones, is used industrially for cutting, drilling, and abrasion of all kinds of materials as well as being used as jewelry. The diamond can be used in industry even if it is of low quality and even in powder form.
All of the stones used are imported since most countries are completely foreign-dependent on precious stones. Diamonds are not produced in these countries. However, there is a demand for diamonds both for use in industry and for jewelry making. In recent years, the use of diamonds has become increasingly widespread due to the development of the jewelry industry and the increase in exports.
As it is known, diamond is one of the most widely used and best known ornamental stones in the world. However, we know the features of the diamond, the features that distinguish this ornamental stone from its counterparts, and that the diamond is valued not only as raw but because of some cut, shine, cleanliness, etc. features. I will evaluate the formation of diamond, how it came to the point where it can be used as an ornamental stone and how it is used in the jewelry industry. Depending on this purpose, how the diamond is formed, how it turns into an ornamental stone, and its place in the world market are important.
Properties of Commercial Diamonds
Mineralogically, diamond is the cubic high-pressure phase of elemental carbon characterized by its thermal conductivity, distribution (0.044), very high density (3.51 gr/cm3), perfect octahedral cleavage, and is the hardest material (10) according to the Mohs hardness scale. At the same time, history shows that the diamond is the most valuable and desirable of all jewelry. In modern times, this is further supported by ingenious discourses such as the extreme durability of diamond, its formation deep within the Earth’s interior (> 105 km), and the theme “diamond is eternal” throughout Earth’s earliest history.
Diamond is by definition a mineral composed only of carbon. The carbon atoms in diamond are packed in a dense cubic crystal structure, and due to this crystal structure, it has unique physical and chemical properties. According to the diamond mosh hardness scale, it is the hardest material that can occur naturally, but despite its high hardness, it is a brittle material that can break against a severe force. Another unusual feature of the diamond is that it is resistant to reaction with most chemicals, meaning that diamond is an inert material.
Diamond can only oxidize under high temperatures. Diamond is the hardest mineral, which insulates electricity very well and conducts heat best. Diamond, which is also the mineral with the highest modulus of elasticity, typically has a modulus of elasticity of 1000 GPa. One of the most important properties of diamond is its high refractive index. This property gives the diamond an extraordinary shine, making it an attractive and extremely precious stone.
Diamond also has high thermal conductivity, making it a valuable component in a wide variety of technological applications. In nature, carbon atoms crystallize only with the crystal structure of diamond at pressures exceeding tens of thousands of bars. At lower pressures, graphite is the stable form of carbon. Unlike diamond, graphite consists of carbon atoms that are weakly bonded to each other. With this crystal structure, graphite is among the softest minerals, while diamond is the hardest.
Diamond Trade Around the World
When we look briefly at the history of diamond production, it is seen that world diamond production was made from quarries in Sri Lanka and India between 800 BC and 1725 AD. It is seen that Brazil was the main producer in the 18th and 19th centuries, while production was mainly made in South Africa, Zaire, and Russia in the 20th century. In the 1980s, Australia joined this list with its large-scale production.
Today, in the production of gem-quality diamonds, Australia takes the lead (18.312.000 carats) in 1995, followed by Botswana, Russia, South Africa, Zaire, Namibia, Brazil, and Angola, with a total world production of 53 million carats. Australia takes first place in the production of industrial quality diamonds (22,381,000 carats), followed by Zaire, Russia, South Africa, Botswana, Brazil, and China. The world’s total production is 58 million carats.
The world diamond production, which has been going on for more than 2000 years, corresponds to less than 400 tons in total. In the world, except for Russia, Australia, and some small producers, the name “De Beers” is associated with diamonds. Although its effect on production is limited, De Beers is able to direct the market as it wishes with its stocks and controlled sales made by its own Central Sales Organization.
It is said that De Beers, with an annual sales turnover of approximately 4.5 billion USD, holds 80% of the jewelry diamond market. With the supply-demand balance being maintained, the diamond becomes a strategic investment. As in the Iranian revolution, some opponents, who had to leave their countries, choose to turn their wealth into diamonds and take them abroad.
It is said that 80% of the gem-quality raw diamonds are bought and sold in Antwerp, Belgium, which is considered the heart of the world diamond market. This city has extensions to many parts of the world: 47th Street on the west side of New York, Hatton Garden in London, high-rise offices in Ramat Gan in Tel Aviv, plus the Opera House district in Mumbai and other parts of India. In these diamond cities of India, a mix of modern technology and cheap labor processes less than one carat of stones into polished jewelry for approximately 800,000 workers for an average wage of US$80 per week.
Silk and Its Features
Silk is the name given to the yarn consisting of very fine, soft, and shiny fiber used in fabric and weaving after being brought to the state of yarn after certain stages. Silk is obtained by unraveling the cocoons knitted by the caterpillar, called the silkworm, which grows by feeding on mulberry leaves. As the yarn is made from this fiber, fabric weaving is also carried out. Silk thread is very strong and flexible. Silk is a very valuable and special thread for special embroidery or sewing projects.
It is the most valuable of all-natural fibers in nature. It adds a soft and flamboyant shine to your sewing. There are three types of silk types used in manufacturing. These are silk thread which is obtained by joining multiple strands of silk, twisted silk which is obtained by twisting and then joining the silk thread, and lightly twisted thread. Cocoons that are woven by silkworms are classified according to quality, size, and color. The silkworm caterpillar turns into a chrysalis after spinning its cocoon. It is possible to draw 365-730 meters of silk wire from a quality cocoon.
500-600 cocoons weigh approximately one kilogram. 1 kilogram of silk is obtained from 10 kilograms of cocoons. Silk thread goes through many stages until it is obtained. While the number of cocoons to be unwound is adjusted according to the thickness of the wire desired to be obtained, the existing wires are pasted through the thin material and adhered to each other. It is thoroughly fused by different processes and wound on a spinning wheel. The yarn that becomes a skein in this way is called “raw silk”. This first process is called the yarn drawing phase. After that, the second phase is the spinning phase.
At this stage, the raw silk yarn is turned into a smooth yarn, and twisting is required to increase its resistance. The silk obtained in this way is called “processed silk”. Depending on the cleaning stage, silks of various softness are obtained. Silk threads are finally coated with another material in order to thicken it, increase its weight, and make it easier to weave. Silk fabric, produced from silk thread, is one of the elements used to highlight stylish dresses. There are also areas of use as silk scarves, sheets, curtains, and covers. Since silk fabric is difficult to weave purely, it is common to use with other yarns.
Collecting Silk Fiber and Its Usage Areas
Silk is a fiber of animal origin that looks beautiful and smooth, is soft, shiny, and durable, and can be easily and well dyed. Silk, which has been playing an important role in the economic life of people for over 4000 years, has been transported to Europe over the years following the silk road passing through China, India, Tashkent, Baghdad, Damascus, and Istanbul. During this time, silk found buyers as a more valuable product than gold. According to estimates, sericulture first started in northeast China.
Mulberry cultivation is the first stage in sericulture. Since mulberry trees are perennial, careful and good selection should be made before planting. Leaf production of the desired quality is possible with a good selection. In the selection of mulberry; Leaf yield, leaf quality, compatibility with soil and climatic conditions, compatibility with silkworm feeding method, and lastly, resistance to diseases and pests should be taken into consideration.
Mulberry sheds should be close to the main roads, should be at least 100 meters away from the areas requiring agricultural struggle, should not be established on lands with a slope of more than 15 degrees, away from industrial centers such as factories and mines that produce smoke and soot. Attention should be paid to mulberry diseases, and disease control should be carried out with appropriate methods in place and on time. Instead of using medicine in diseases such as leaf rust, red leaf spot, mulberry tongue fungus, it is useful to cut branches and leaves and burn them.
Mulberry silk obtained from silkworms feeding on mulberry leaves constitutes 95 percent of the world’s silk production. Since silk thread can be drawn continuously from the cocoons of silkworm (Bombyx Mori) fed with mulberry, raw silk thread used in industry is obtained. Silk comes from Bombyx Mori, which has been domesticated for over 4000 years.
The Life Cycle of Silk
Seeds: Silkworm seeds are very small. Nearly 2000 seeds are only 1 gr. Seeds are 1-1.3 mm long and 0.9-1.2 mm wide.
Caterpillars: Silkworm caterpillars are dark brown and black in color when they hatch from larvae. The head of the caterpillars is large and the body is covered with hairs. As the age progresses, the skin color becomes lighter and the skin takes on a smooth appearance.
Head: The head consists of 6 segments (rings). The 2nd segment contains the antennae, the 4th segment contains the lower jaw, the 5th segment contains the upper jaw, and the 6th segment contains the lip organs. There are 6 pairs of simple eyes on the upper sides of the antennae. Antennas are 1 pair and consist of 6 parts, lower jaw cuts, upper jaw extensions detect the taste of food. Between the lower jaw are the lower and upper lips and the filigree hole where the silk is secreted.
Chest: The chest consists of 3 rings and there are 3 pairs of feet on the underside. These feet are not used for clinging and climbing, they have a holding feature and are used to hold the leaves while eating.
Abdomen: The abdomen consists of 11 body rings. 9 abdominal rings and the other two rings are combined in the tail, and there are tail legs or 5 pairs of false abdominal feet from the lower side. There is a pair of abdominal legs each on the underside of the 3-4-5 and 6th abdominal legs and in the last abdominal ring. The tail horn (spur) is located on the 8th abdominal ring. On the lower part of the 8th and 9th rings, there are signs of gender discrimination.
Only their development can be seen between the fourth and fifth years of the insect. The female sex markings can be seen in the form of milky white dots on the underside of the eighth and ninth rings. They are called “Ishwata” glands. The male sex sign is milky white, between the 8th and 9th abdominal rings, and has the appearance of a protrusion in the middle and is called the “Herold” gut.
Silkworm Breeding
Cleaning and Disinfection: 7-10 days before feeding, the feeding area should be cleaned and whitewashed with lime. In addition, by placing disinfectant mats at the entrance of the feeding room and houses, the transmission of microbes with shoes is prevented. Insect houses should have features that can be easily cleaned, ventilated, temperature and humidity-controlled.
Flushing: Special egg boxes are used for flushing. The infested caterpillars are only 3 mm long and 0.5 g in weight. They are covered with hairs. The sprouting caterpillars are taken to special decks. Crayfish can be mobile or suspended from the ceiling. For easy cleaning, the height of the first deck from the ground should be at least 25 cm. The height between the two decks is set as 70-90 cm.
Feeding and Care of Silkworms: Silkworms produce cocoon products in a short period of 35-40 days without much expense and work. However, it should be carefully looked after and fed. There is the possibility of feeding in two seasons. Feeding in April, May, and June is called spring feeding, and feeding in August and September is called autumn feeding. The feeding house should be a place that can be cleaned and whose temperature and humidity can be controlled. During the caterpillar period, the silkworm eats white mulberry leaves and goes to sleep 4 times.
The insect changes its shirt after the dormant period. It remains motionless for 24 hours without eating mulberry leaves. The period between two periods of sleep is called an age 1. The 2nd and 3rd years are the young silkworms, the 4th and 5th years are the advanced silkworm stage. Mulberry leaves are given by chopping at the first ages, there is no need to chop the leaves in advanced ages. At the end of the 5th year, which takes about 3 days, insects stop eating. The stomach is completely emptied and the suspension period begins.
Hanger and Cocoon Harvesting: For the insects maturing in our country to weave their cocoons; vegetable hangers such as wheat, rye, paddy, mustard, mullein, heather water saddle, heather, oak, pine, plastic, and corrugated hangers are used. Silkworms can be suspended individually by hand, or they can be suspended on their own. Suspended silkworms evacuate their feces and urine and are ready to spin the cocoon. First, it secretes some silk called cocoon cotton, which allows the cocoon to hold, and attaches itself to the hanger.
The silkworm begins to weave the cocoon from the outside and continues to weave inward. It spins its cocoon by extracting the sticky substance called sericin from the glands under its chin as threads and moving its head like the figure eight. It traps itself inside the cocoon. This takes an average of three days. The caterpillar that weaves its cocoon remains shrunken and shrunken inside its cocoon and turns into a chrysalis. If the boll harvest is done before the chrysalis matures, stained and low-quality bolls are obtained.
The best time for the cocoon harvest is 10-11 days after the start of the cocoon crop. Being late in the harvest causes financial losses. The chrysalis pierces the cocoon to become a butterfly and mate. Silk cannot be drawn from punctured cocoons. Cocoons are collected one week after they are knitted and finished. The chrysalis in the cocoon is killed without damaging the cocoon. This process is called strangulation and is performed in two ways:
- Vapor
- Hot Air: Chrysalis is killed with hot air in special furnaces working with electricity. Cocoons come out dry from the oven.
Obtaining Silk Fiber
Sericin, secreted from the mouth of the silkworm, has a typical gum property. Therefore, the silk strands stick together. In order for the silk to be drawn, sericin must be softened. Sericin softens in hot water of 50-60 degrees. When the softened cocoons of the sericins are touched with a tool such as a brush or a broom, the ends of the silk threads can be caught. This is a tricky process. After the silk threads called whip heads, which are wasted during the discovery of the ends that can be wound continuously, the silk fibers are wound on a spinning wheel.
Silks are made into hanks. This silk is called raw silk and is quite stiff due to the sericin substance. Cooking is done by boiling silk in soapy water. After the cooking process, as sericin melts, raw silk loses 20-30 percent of its weight. Various processes are applied and put into use in order to gain weight and cast the silk. Raw silk is used in weaving. If a few strands of raw silk are brought together and twisted in twisting machines, twisted “processed silk” is produced.
The number of twists on 1 meter of raw silk is adjusted according to the place where the silk can be used, that is, where it will be used as warp and weft yarn. The quality of silk is measured by the same thickness of the silk strands, the absence of roughness, and bristle clutter. Silk threads gaining their weight, casting, and beauty in special ovens are dried in hanks. After this process, silk hanks sent to the factories are prepared for winding on reels. Since there are three types of silk yarn, yarn is produced in three ways:
- Spinning Wheel Silk: Flament (continuous fiber) silk is turned into yarn by giving some twist during its pulling from the cocoon and wrapped in bobbins.
- Alum Silk: The fiber residues formed during the spinning of the spinning wheel are spun similar to the worsted spinning method.
- Buret Silk: Very short scraps and shredded silk fibers are spun in a similar way to the woolen spinning method.
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