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Quizzes > Quizzes for Business > Education

Take the Gemstone Properties Knowledge Quiz

Explore Gemstone Characteristics in This Quiz

Difficulty: Moderate
Questions: 20
Learning OutcomesStudy Material
Colorful paper art depicting various gemstones for a Gemstone Properties Knowledge Quiz.

Ready to dive into the dazzling world of gemstones? Joanna Weib invites geology students and jewelry enthusiasts to take this Gemstone Properties Knowledge Quiz and strengthen their grasp of hardness, refractive index, and classification. Educators and self-learners will love how each question deepens mineralogical insight. Feel free to adapt this quiz in our editor to match your lesson plan or study needs. For more material science challenges, check out the Materials Characterization and Properties Midterm Quiz and the Knowledge Assessment Quiz , or browse all quizzes for endless learning opportunities.

Which gemstone property measures the resistance of a gem to being scratched?
Luster
Hardness
Density
Refractive index
Hardness is defined as a material's resistance to scratching or abrasion. It is quantified by scales such as the Mohs hardness scale. Other properties like density and luster describe weight and surface appearance, respectively.
On the Mohs scale, which gemstone is assigned a hardness of 8?
Feldspar
Quartz
Topaz
Corundum
Topaz is ranked 8 on the Mohs hardness scale. Quartz is 7, feldspar (orthoclase) is 6, and corundum (sapphire, ruby) is 9. This scale is a relative ranking of scratch resistance.
Which property describes how much light bends when it enters a gemstone?
Specific gravity
Cleavage
Dispersion
Refractive index
The refractive index measures the degree to which light is bent, or refracted, upon entering a material. Dispersion describes splitting of light into colors, specific gravity is density relative to water, and cleavage is how a gem breaks.
Rubies are chemically classified under which mineral group?
Garnet
Corundum
Silicate
Carbonado
Rubies are the red variety of corundum, which is aluminum oxide (Al₂O₃). Silicates, garnets, and carbonado (a form of diamond) are different chemical classes altogether.
Which optical instrument uses polarized light to test for internal strain and double refraction in gemstones?
Loupe
Refractometer
Dichroscope
Polariscope
A polariscope uses polarized light to reveal internal strain patterns and double refraction. A refractometer measures refractive index, a loupe is for magnification, and a dichroscope observes pleochroism.
An unknown stone scratches quartz (Mohs 7) but is itself scratched by topaz (Mohs 8). What is its approximate hardness?
9
6
7.5
8.5
If a mineral can scratch quartz (7) but is scratched by topaz (8), its hardness lies between 7 and 8. A midpoint estimate is around 7.5 on the Mohs scale.
Which gemstone has the highest refractive index?
Quartz
Spinel
Diamond
Topaz
Diamond has a refractive index of approximately 2.42, higher than quartz (~1.54), spinel (~1.72 - 1.74), and topaz (~1.61 - 1.62). The RI correlates with brilliance in gemstones.
The splitting of a light ray into two rays as it passes through a gemstone is called what?
Chatoyancy
Birefringence
Dispersion
Pleochroism
Birefringence (double refraction) occurs when a light ray splits into two rays traveling at different speeds. Pleochroism is color change, dispersion is color separation, and chatoyancy is a cat's-eye effect.
Which gemstone belongs to the phosphate class of minerals?
Turquoise
Topaz
Olivine
Beryl
Turquoise is a hydrated copper aluminum phosphate. Beryl is a cyclosilicate, olivine is a nesosilicate, and topaz is a fluorosilicate.
A gemstone tested on a refractometer shows an RI of 1.544 - 1.553. Which gem is this most likely?
Tourmaline
Quartz
Spinel
Beryl
Quartz has a refractive index range of about 1.544 - 1.553. Beryl, tourmaline, and spinel all have distinctly different RI ranges.
Which inclusion pattern, consisting of liquid, vapor, and crystal phases, is diagnostic of natural emeralds?
Silk
Feather
Crystal
Three-phase
Three-phase inclusions (liquid, gas, and crystal) are characteristic of natural emeralds. Feathers are fractures, silk is rutile needles, and crystal is a solid inclusion only.
Which gemstone commonly exhibits strong pleochroism showing pink and green colors?
Quartz
Topaz
Tourmaline
Spinel
Tourmaline, especially bi-color varieties, shows strong pleochroism with distinct color changes. Quartz, spinel, and topaz have much weaker or no pleochroism.
Which mineral has the highest birefringence value?
Diamond
Quartz
Topaz
Calcite
Calcite has a very high birefringence (~0.172), much greater than quartz (~0.009), diamond (~0.044), or topaz (~0.010). Birefringence is the difference between two refractive indices.
In a scratch test, a specimen fails to scratch calcite (Mohs 3) but easily scratches gypsum (Mohs 2). What is its hardness range?
3 - 4
2 - 3
1 - 2.5
4 - 5
Since the specimen scratches gypsum (2) but not calcite (3), its hardness lies between 2 and 3 on the Mohs scale. This interval indicates intermediate resistance.
Which gemstone crystallizes in the rhombohedral system?
Orthoclase
Calcite
Quartz
Beryl
Calcite crystallizes in the trigonal (often called rhombohedral) system. Quartz is trigonal too but typically described differently, while beryl is hexagonal and orthoclase is monoclinic.
A gemstone measures refractive indices of 1.650 - 1.690 with birefringence of about 0.036. Which gem matches these values?
Tourmaline
Peridot
Spinel
Garnet
Peridot has a refractive index range near 1.650 - 1.690 and high birefringence around 0.036. Tourmaline, garnet, and spinel have distinctly different optical properties.
Under magnification, a diamond shows a fingerprint-like inclusion pattern of interconnected fluid-filled cavities. What does this indicate?
Natural origin
Treated diamond
Imitation
Synthetic origin
Fingerprint inclusions are networks of fluid-filled cavities typical of natural diamond growth. They are not found in most synthetics, treated stones, or imitations.
Which gemstone is characterized by parallel rutile needle inclusions known as "silk"?
Sapphire
Quartz
Emerald
Tourmaline
Silk refers to fine parallel rutile needles, commonly found in sapphire. These inclusions can produce a silky sheen or star effect in corundum.
A gemstone shows clear doubling of back facet junctions under a 10Ã - loupe. Which gem is this most indicative of?
Garnet
Topaz
Spinel
Zircon
Zircon has high birefringence that produces visible doubling of facet junctions under magnification. Spinel, topaz, and garnet are singly refractive and do not show this effect.
The formula Be3Al2(Si6O18) corresponds to which silicate classification?
Inosilicate
Cyclosilicate
Phyllosilicate
Nesosilicate
Be3Al2(Si6O18) is the formula for beryl, a cyclosilicate with six-membered silicate rings. Nesosilicates have isolated tetrahedra; inosilicates form chains; phyllosilicates form sheets.
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Learning Outcomes

  1. Identify key gemstone properties and their significance
  2. Analyze gemstone hardness using the Mohs scale
  3. Evaluate refractive index differences in gemstones
  4. Classify gemstones by chemical composition
  5. Apply optical tests to distinguish gemstone types
  6. Interpret inclusion patterns to assess gemstone quality

Cheat Sheet

  1. Understand the Mohs Scale of Hardness - Think of the Mohs Scale as a rock concert ranking where talc kicks off at 1 and diamond headlines at 10. Each mineral "scratches" another to prove its toughness, so a 7 (quartz) can scratch a 6 (feldspar) but not an 8 (topaz). This hands-on test helps you quickly gauge a gem's durability. Physical Properties of Gemstones
  2. Learn About Refractive Index (RI) - Refractive Index is the secret ingredient that bends light as it dives into a gemstone, creating that breathtaking sparkle. Diamonds rock a high RI (~2.42), which explains their legendary brilliance. Use RI = speed of light in vacuum / speed of light in the material to measure how much a gem bends light. Optical Properties of Gems
  3. Recognize Pleochroism in Gemstones - Pleochroism is like your gem's personal color-shifting magic show - turn it, and it reveals new hues! Iolite, for example, jumps between blue, violet, and yellow-brown when you peer at different angles. Spotting pleochroism is a fun way to identify gems in the field or the lab. Optical Properties of Gemstones
  4. Identify Gemstone Cleavage and Fracture - Cleavage is a gem's tendency to split along smooth planes, while fracture shows how it breaks when there's no easy parting line. Knowing these break patterns helps you predict cutting outcomes and assess durability. Think of cleavage as a gem's "path of least resistance." Physical Properties of Gemstones
  5. Explore Gemstone Dispersion (Fire) - Dispersion is the dazzling trick where white light fans out into rainbow colors inside a gem, creating that coveted "fire." Diamonds are masters of dispersion, producing fiery flashes at every turn. Observing dispersion gives clues about a gem's brilliance and optical quality. Optical Properties of Gemstones
  6. Understand Specific Gravity (SG) - Specific Gravity compares a gem's density to water, letting you tell a heavy garnet (SG 3.4 - 4.3) from a light quartz (SG ~2.65). This weight check is a fast way to narrow down candidates when you're testing unknown stones. Carry a pocket balance and a small vial of water for instant SG fun! Physical Properties of Gemstones
  7. Recognize Optical Phenomena in Gemstones - From asterism (star effects) to chatoyancy (cat's eye), these sparkly shows happen when light interacts with internal fibers or inclusions. Rubies and sapphires can dazzle you with a six-ray star at the right cut and orientation. Spotting these effects is like discovering hidden superpowers in your stones! Gemstone Optical Properties
  8. Classify Gemstones by Chemical Composition - Gems are grouped by what they're made of, so corundum hosts both rubies and sapphires, and their color heroes are just trace elements. Understanding these families helps you predict properties like hardness, cleavage, and optical behavior. Chemical classification is your treasure map in the gem world. Physical Properties of Gemstones
  9. Apply Optical Tests for Gem Identification - Grab a refractometer to measure RI, a polariscope to spot pleochroism, and a dichroscope to reveal hidden color shifts. These gadgets turn gem ID into an interactive lab adventure. Mastering these tests makes you the Sherlock Holmes of gemstones! Optics in Gemology
  10. Interpret Inclusions to Assess Gem Quality - Inclusions are the tiny fingerprints inside gems that tell tales of their formation and value. Some, like rutile needles in star sapphires, score bonus points for creating gorgeous optical effects. Learning to read inclusions transforms every stone into a storybook. Gemstone Optical Properties
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