Dolphin, Basil

Dolphin, Basil

Address: Healthworks, Muhlenberg Hospital, 2545 Schoenersville Road, Behtlehem, Pennsylvania

Country: United States

Phone: 1 (610) 861-2249

Fax: 1 (610) 861-8034

Education: MD; MPH

Saturday, 02 April 2011 21:03

Synthetic Gems

Synthetic gems are chemically and structurally identical to stones found in nature. Imitation gems, in contrast, are stones that are made to appear similar to a particular gem. There are a few basic processes that produce a variety of gem stones. Synthetic gems include garnet, spinel, emerald, sapphire and diamond. Most of these stones are produced for use in jewellery. Diamonds are used as abrasives, while rubies and garnets are used in lasers.

The first synthetic gem used in jewellery was emerald. The process employed in its manufacture is proprietary and kept secret, but probably involves a flux-growth method in which silicates of alumina and beryllium with additions of chromium for colour are melted together. Emeralds crystallize out of the flux. It may take a year to produce stones by this process.

The Verneuil or flame-fusion process is used in the production of sapphire and ruby. It requires large amounts of hydrogen and oxygen, therefore consuming great amounts of energy. This process involves heating a seed crystal with an oxyhydrogen flame until the surface is liquid. Powered raw material such as AI2O3 for sapphire is added carefully. As the raw material becomes molten, the seed crystal is slowly withdrawn from the flame, causing the liquid furthest from the flame to solidify. The end closest to the flame is still liquid and ready for more raw material. The end result is the formation of a rod-like crystal. Sundry colours are created by adding small amounts of various metal ions to the raw materials. Ruby is created by replacing 0.1% of its aluminium ions with chromium atoms.

Spinel, a colourless synthetic germ (MgAI2O4), is made by the Verneuil process. Along with sapphire, spinel is used by industry to provide a wide range of colours for use as birth stones and in class rings. The colour produced by adding the same metal ions will be different in spinel than it will be in sapphire.

Synthetic diamonds are used in industry because of their hardness. Applications for diamonds include cutting, polishing, grinding and drilling. Some of the common uses are cutting and grinding of granite for use in building construction, well drilling and grinding non-ferrous alloys. In addition, processes are being developed that will deposit diamond on surfaces to provide clear, hard, scratch-resistant surfaces.

Diamonds are formed when elemental carbon or graphite is subjected to pressure and heat over time. To create a diamond on the factory floor involves combining graphite and metal catalysts and pressing them together in high heat (up to 1,500 °C). The size and quality of the diamonds are controlled by adjusting the time, pressure and/or heat. Large tungsten carbide dies are used to achieve the high pressures needed to form diamonds in a reasonable period of time. These dies measure up to 2 m across and 20 cm thick, resembling a large doughnut. The mixture of graphite and catalyst is placed in a ceramic gasket, and tapered pistons squeeze from above and below. After a specified time, the gasket containing diamonds is removed from the press. The gaskets are broken away and the diamond-bearing graphite is subjected to a series of agents designed to digest away all material except for the diamonds. The reactants employed are strong agents that are potential sources of significant burns and respiratory injury. Gem-quality diamonds may be produced in the same manner, but the long press times required make this process prohibitively expensive.

Hazards resulting from the manufacture of diamonds include potential exposure to the highly reactive acids and caustic agents in great volumes, noise, dust from forming and breaking of ceramic gaskets, and metal dust exposure. Another potential hazard is created by the failure of the massive carbide dies. After a variable number of uses, the dies fail, posing a trauma hazard if the dies are not isolated. Ergonomic issues arise when the diamonds manufactured are classified and graded. Their small size makes this a tedious and repetitive job.



" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."


Part I. The Body
Cardiovascular System
Physical, Chemical, and Biological Hazards
Digestive System
Mental Health
Mood and Affect
Musculoskeletal System
Nervous System
Renal-Urinary System
Reproductive System
Respiratory System
Sensory Systems
Skin Diseases
Systematic Conditions
Part II. Health Care
First Aid & Emergency Medical Services
Health Protection & Promotion
Occupational Health Services
Part III. Management & Policy
Disability and Work
Education and Training
Case Studies
Ethical Issues
Development, Technology, and Trade
Labour Relations and Human Resource Management
Resources: Information and OSH
Resources, Institutional, Structural and Legal
Community level
Regional and National Examples
International, Government and Non-Governmental Safety and Health
Work and Workers
Worker's Compensation Systems
Topics In Workers Compensation Systems
Part IV. Tools and Approaches
Biological Monitoring
Epidemiology and Statistics
Goals, Principles and Methods
Physical and Physiological Aspects
Organizational Aspects of Work
Work Systems Design
Designing for Everyone
Diversity and Importance of Ergonomics
Occupational Hygiene
Personal Protection
Record Systems and Surveillance
General Principles of Toxicology
Mechanisms of Toxicity
Toxicology Test Methods
Regulatory Toxicology
Part V. Psychosocial and Organizational Factors
Psychosocial and Organizational Factors
Theories of Job Stress
Chronic Health Effects
Stress Reactions
Individual Factors
Career Development
Macro-Organizational Factors
Job Security
Interpersonal Factors
Factors Intrinsic to the Job
Organizations and Health and Safety
Part VI. General Hazards
Barometric Pressure Increased
Barometric Pressure Reduced
Biological Hazards
Disasters, Natural and Technological
Heat and Cold
Hours of Work
Indoor Air Quality
Indoor Environmental Control
Radiation: Ionizing
Radiation: Non-Ionizing
Visual Display Units
Part VII. The Environment
Environmental Health Hazards
Environmental Policy
Environmental Pollution Control
Part VIII. Accidents and Safety Management
Accident Prevention
Audits, Inspections and Investigations
Safety Applications
Safety Policy and Leadership
Safety Programs
Part IX. Chemicals
Using, Storing and Transporting Chemicals
Minerals and Agricultural Chemicals
Metals: Chemical Properties and Toxicity
Part X. Industries Based on Biological Resources
Agriculture and Natural Resources Based Industries
Farming Systems
Food and Fibre Crops
Tree, Bramble and Vine Crops
Specialty Crops
Beverage Crops
Health and Environmental Issues
Beverage Industry
Food Industry
Overview and Health Effects
Food Processing Sectors
Livestock Rearing
Paper and Pulp Industry
Major Sectors and Processes
Disease and Injury Patterns
Part XI. Industries Based on Natural Resources
Iron and Steel
Mining and Quarrying
Oil Exploration and Distribution
Power Generation and Distribution
Part XII. Chemical Industries
Chemical Processing
Examples of Chemical Processing Operations
Oil and Natural Gas
Pharmaceutical Industry
Rubber Industry
Part XIII. Manufacturing Industries
Electrical Appliances and Equipment
Metal Processing and Metal Working Industry
Smelting and Refining Operations
Metal Processing and Metal Working
Microelectronics and Semiconductors
Glass, Pottery and Related Materials
Printing, Photography and Reproduction Industry
Part XIV. Textile and Apparel Industries
Clothing and Finished Textile Products
Leather, Fur and Footwear
Textile Goods Industry
Part XV. Transport Industries
Aerospace Manufacture and Maintenance
Motor Vehicles and Heavy Equipment
Ship and Boat Building and Repair
Part XVI. Construction
Health, Prevention and Management
Major Sectors and Their Hazards
Tools, Equipment and Materials
Part XVII. Services and Trade
Education and Training Services
Emergency and Security Services
Emergency and Security Services Resources
Entertainment and the Arts
Arts and Crafts
Performing and Media Arts
Entertainment and the Arts Resources
Health Care Facilities and Services
Ergonomics and Health Care
The Physical Environment and Health Care
Healthcare Workers and Infectious Diseases
Chemicals in the Health Care Environment
The Hospital Environment
Health Care Facilities and Services Resources
Hotels and Restaurants
Office and Retail Trades
Personal and Community Services
Public and Government Services
Transport Industry and Warehousing
Air Transport
Road Transport
Rail Transport
Water Transport
Part XVIII. Guides
Guide to Occupations
Guide to Chemicals
Guide to Units and Abbreviations