26 Questions
What is the ideal jewelry type for rubies due to their hardness?
Frequently worn jewelry
Why is laboratory analysis required for Beryllium lattice diffusion in Ruby's ?
Because it is difficult to detect
What is the cause of fluorescence in rubies?
The presence of chromium
What is the primary source of the world's rubies?
Africa
Why should a stone not be described by its source name?
Unless you're sure the stone came from that source
What is the most important ruby source?
The Montepuez area of Mozambique
Why do rubies typically form in marble deposits?
Due to the geological formation process
What is the purpose of heat-treating rubies?
To improve color and clarity
Which of the following is NOT a major ruby cutting and trading center?
Myanmar
What is the effect of high levels of iron in basalt-hosted rubies?
It inhibits fluorescence
What is the most valuable ruby color?
Red to purplish-red
What is the typical Mohs hardness scale rating of ruby?
9
What treatment is not stable, and can affect the appearance of a ruby over time?
Clarity enhancement
What is the significance of Thailand in the ruby industry?
It's the largest ruby cutting and trading center
What is the common practice with regards to heat-treating rubies?
Almost always heat-treated
What is the primary factor that determines the value of a ruby?
Color
What is the significance of Mogok, Myanmar?
It's the most historically important ruby source
What is the characteristic of lead-glass treated rubies that are considered composites or manufactured?
High proportions of filler
Why is Africa replacing Southeast Asia as the primary source of rubies?
The reason is not specified in the text
What is the common association between chromium and rubies?
Chromium causes rubies to be red
What is the characteristic of the finest rubies?
Formed in marble deposits
When can Ruby's command. the highest price per carat of all colored stones?
When untreated
Ruby deposits in Thailand and Cambodia are associated with ...?
alkali-basalt
The Central Asia, Afghanistan and Tajikistan rubies are found in what type of deposit ?
Marble
Low temperature heat treatment sometimes ........?
Improve ruby's color
The introduction of the first synthetic ruby's did what ?
Destabilized the natural gem market
Study Notes
Ruby Characteristics
- Ruby rates 9 on the Mohs hardness scale, making it ideal for frequently worn jewelry.
- The most valuable ruby colors are red to slightly purplish red with medium to medium-dark tone and vivid saturation.
- Chromium, a trace element, causes rubies to be red and can also cause fluorescence, which intensifies body color.
Treatment and Enhancement
- Beryllium lattice diffusion is difficult to detect and often requires laboratory analysis.
- Clarity enhancement is not stable and a treated ruby's appearance might change over time.
- Lead-glass treated rubies may contain a high proportion of filler, making them considered composites or manufactured products by gem labs.
Sources and Markets
- Thailand is the world's largest ruby cutting, treatment, and trading center.
- Africa has replaced Southeast Asia as the source of the majority of the world's ruby.
- The Montepuez area of Mozambique is the world's most important ruby source.
- Mogok, Myanmar, is the most historically important ruby source.
- Mines in Mong Hsu, Myanmar, supplied most of the world's commercial-quality rubies through the 1990s.
Notable Facts
- Rubies are almost always heat-treated to improve color and clarity.
- Along with Thailand, the world's major ruby cutting and trading centers include China, Sri Lanka, and India.
- Never describe a stone by a source name unless you're sure the stone came from that source.
Ruby Characteristics
- Ruby rates 9 on the Mohs hardness scale, making it ideal for frequently worn jewelry.
- The most valuable ruby colors are red to slightly purplish red with medium to medium-dark tone and vivid saturation.
- Chromium, a trace element, causes rubies to be red and can also cause fluorescence, which intensifies body color.
Treatment and Enhancement
- Beryllium lattice diffusion is difficult to detect and often requires laboratory analysis.
- Clarity enhancement is not stable and a treated ruby's appearance might change over time.
- Lead-glass treated rubies may contain a high proportion of filler, making them considered composites or manufactured products by gem labs.
Sources and Markets
- Thailand is the world's largest ruby cutting, treatment, and trading center.
- Africa has replaced Southeast Asia as the source of the majority of the world's ruby.
- The Montepuez area of Mozambique is the world's most important ruby source.
- Mogok, Myanmar, is the most historically important ruby source.
- Mines in Mong Hsu, Myanmar, supplied most of the world's commercial-quality rubies through the 1990s.
Notable Facts
- Rubies are almost always heat-treated to improve color and clarity.
- Along with Thailand, the world's major ruby cutting and trading centers include China, Sri Lanka, and India.
- Never describe a stone by a source name unless you're sure the stone came from that source.
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