Selected Answer: a. an optical phenomenon resulting in 6 or 12 pointed star reflectance, caused by inclusion of rutile needles

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1 Question 1 1 out of 1 points Asterism in corundum is: a. an optical phenomenon resulting in 6 or 12 pointed star reflectance, caused by inclusion of rutile needles Question 2 1 out of 1 points The value of faceted gem corundum is based on: e. Colour, Country of Origin, Carat, Cut, & Clarity Question 3 1 out of 1 points Treatment of corundum is typically done to rough stones because: a. High heat can create cracks in a cut stone, decreasing its value Question 4 1 out of 1 points What is the common form of euhedral corundum crystals? hexagonal prism c. "barrel" shaped tapering Question 5 1 out of 1 points Which mineral has historically been sometimes misclassified as ruby? a. red spinel Question 6 1 out of 1 points Which of the following is not a variety of gem corundum? d. tanzanite

2 Question 7 1 out of 1 points Which of the following phrases will make this statement TRUE? Binocular gemological microscopes. d. will reveal more inclusions than a 10X Loupe Question 8 1 out of 1 points Considering the visible absorption spectra of emerald, alexandrite and ruby (all Cr 3+ bearing gems), which of the following statements is TRUE? c. Each has a strong absorption band that is slightly shifted from one another (emerald@~650 nm, alexandrite@~585 nm, ruby@~570 nm) Question 9 1 out of 1 points Tourmaline with a pink core and green rim is often called. c. Watermelon tourmaline Question 10 1 out of 1 points A fractionated magma is one which has: d. many elements removed by the crystallization of earlier-stage (higher temperature) minerals Question 11 1 out of 1 points If you wished to find a variety of rough gemstones to keep in a collection, where might be a good place to start looking (besides a gem and mineral show)? rich in pegmatites d. an area known to be

3 Question 12 1 out of 1 points Which element is considered essential to the crystallographic structure of tourmaline: b. Boron (B) Question 13 1 out of 1 points The parent mineral spodumene gives rise to which of the following gem varieties? b. kunzite Question 14 1 out of 1 points A fluxing agent helps pegmatites to grow bigger crystals because: c. all of these Question 15 1 out of 1 points The blue of Lapis Lazuli is primarily caused by which of the following minerals? hauyne c. Lazurite, sodalite, and Question 16 1 out of 1 points Lapis lazuli is a gemstone composed mostly of (check all that apply, wrong answers penalized.): Question 17 1 out of 1 points b. calcite c. lazurite e. pyrite Most jade in British Columbia is. c. nephrite Question out of 1 points

4 Which of the following are organic gems? Check all that apply, wrong answers penalized. Selected Answers: a. amber b. coral d. pearl Question 19 1 out of 1 points Aside from gem aspects, spodumene is valuable because one of its essential elements,, is otherwise difficult to find in high concentrations for mining: c. lithium Question 20 1 out of 1 points What are(is) the chromophore(s) for tanzanite and which gems share these chromophore(s)? emerald e. Vanadium; ruby and Question 1 0 out of 1 points Why are "star" corundum gems in the form of cabochons typically larger (more carats) than faceted stones? d. The rutile silk that produces the asterism is dense. Consequently, its inclusion in the gemstone significantly adds to the overall weight. Question 2 1 out of 1 points Asterism in corundum is: b. an optical phenomenon resulting in 6 or 12 pointed star reflectance, caused by inclusion of rutile needles Question 3 1 out of 1 points

5 The "Black Prince's Ruby" is actually. c. spinel Question 4 1 out of 1 points Which of the following is a common source of gem corundum? b. Dirty Marbles Question 5 1 out of 1 points Ruby gets its colour from which substitution in the crystal structure of corundum: a. approximately 1% (by weight) of Cr2O3 for Al2O3 Question 6 1 out of 1 points What is the common form of euhedral corundum crystals? hexagonal prism b. "barrel" shaped tapering Question 7 1 out of 1 points Which of the following phrases will make this statement TRUE? Binocular gemological microscopes. c. will reveal more inclusions than a 10X Loupe Question 8 1 out of 1 points What is the most important and reliable tool used in rock and gem identification? c. Unaided eye Question 9 1 out of 1 points

6 The NYF subtype of rare-element pegmatites produces more gemstones than LCT type False Question 10 1 out of 1 points Coating topaz gemstones with a film improves their appearance in which manner? optical effects a. creates a variety of Question 11 1 out of 1 points What are the two main colours of gem varieties of spodumene: d. pink and green Question 12 1 out of 1 points Topaz crystals can come in a variety of sizes and can be very large. However, the largest crystals are not always of gem quality. Which range does the largest cut topaz fall into? a. >10000 carats Question 13 1 out of 1 points Which of the following P-T (pressuretemperature) regimes for pegmatites produces the most gemstones (that is: which one represents the category called rare-element pegmatite ): a. low T, low P Question 14 1 out of 1 points Pegmatites are in a large part defined by the fact that they contain very large crystals. What else could be considered as (a) distinguishing characteristic(s) of a granitic pegmatite? Check

7 all that apply, wrong answers penalized. Question 15 1 out of 1 points b. enriched in rare elements e. forms dykes Turquoise requires which of these metallic elements in its crystal structure? c. copper Question 16 1 out of 1 points What are the two main colours shown by fine quality alexandrite? c. red and green Question 17 1 out of 1 points What is the chromophore for alexandrite? d. Cr Question out of 1 points In which of the following ways can heat treatment improve corundum? Check all that apply, wrong answers penalized. Selected Answers: a. Allows Be to enter the crystal structure of colourless corundum for the creation of Padparadscha sapphires b. Allows solid inclusions to be resorbed into the crystal structure d. Allows fluid and fracture-type inclusions to anneal Question 19 0 out of 1 points Bicoloured topaz crystals develop because: c. during initial crystallization, drastic shifts in the temperature

8 causes the crystal lattice to bend, similar in behaviour to organic protein folding; each side of the bend absorbs a different part of the light spectrum Question out of 1 points Which of the following are pegmatite gems? Check all that apply, wrong answers penalized. Selected Answers: a. kunzite d. topaz e. dravite Question 1 1 out of 1 points Which of the following BEST desribes the chemical formula of corundum? e. aluminum oxide Question 2 1 out of 1 points The "Black Prince's Ruby" is actually. e. spinel Question 3 1 out of 1 points Which of the following is a common source of gem corundum? a. Dirty Marbles Question 4 1 out of 1 points Historically, where were the most valuable rubies mined? d. Burma Question 5 1 out of 1 points How could you tell the difference between an

9 uncut blue beryl and an uncut blue corundum? a. corundum is harder; corundum has tapered (rather than flat) ends Question 6 1 out of 1 points Which of the following is NOT a common source of gem corundum? c. Granite Question 7 1 out of 1 points Why are immersion cells (or vessels) a useful tool for gemologists? (Check all that apply; wrong answers will be penalized) Selected Answers: a. They can help show if a gemstone is a composite stone (doublet or triplet) c. They can be used to help inspect a gemstone for diffusion treatments d. They can be used to determine the refractive index of a gemstone Question 8 1 out of 1 points How does fluorescence in minerals work? c. Atoms moved to a higher energy excited state by UV light drop back to their ground state by releasing energy as visible light. Question 9 1 out of 1 points The parent mineral spodumene gives rise to which of the following gem varieties? c. kunzite Question 10 1 out of 1 points Fluxing agents help pegmatites grow bigger crystals in a few ways. Which of the following is NOT one of the ways fluxing agents help crystal

10 growth? d. They keep large volumes of gas trapped in the magma which creates spaces (pockets) for large crystals to form Question 11 1 out of 1 points Pegmatites are in large part defined by the fact that they contain very large crystals; dykes with small crystals are just called dykes. Just what is large, as far as crystals in pegmatites goes? e. 10 s of metres Question 12 1 out of 1 points What are the four genetic pegmatite groups (families)? b. Abyssal, Muscovite, Rare-element, Miarolitic Question 13 1 out of 1 points Coating topaz gemstones with a film improves their appearance in which manner? optical effects d. creates a variety of Question 14 1 out of 1 points Granitic pegmatites can be enriched in the following rare elements (check all that apply, wrong answers penalized.): Selected Answers: a. Ta d. Li e. Be Question 15 1 out of 1 points Nephrite consists primarily of very fine grained crystals from the mineral group, while

11 jadeite is a rock primarily composed of crystals from the mineral group. a. amphibole, pyroxene Question 16 1 out of 1 points Turquoise requires which of these metallic elements in its crystal structure? d. copper Question 17 1 out of 1 points Famous localities for turquoise include. b. All of these Question 18 1 out of 1 points Corrosion is a problem for gemstone development in pegmatites. Corrosion is when: d. leftover volatiles like carbonate and fluorine dissolve portions of mineral crystals after they form Question out of 1 points Tanzanite has a hardness of 6.5. This makes it softer than the gems: (Check all that apply; wrong answers will be penalized) b. Lapis Lazuli (lazurite) c. Ruby (corundum) e. Kunzite (spodumene) Question 20 1 out of 1 points Topaz and tourmaline are not as highly valued as diamond, beryl, or corundum. This is because, aside from optical properties, topaz and tourmaline do not rank as high when assessing, a desirable property for gemstone

12 longevity. d. hardness

Treated and synthetic gem materials

Treated and synthetic gem materials James E. Shigley GIA Research, Gemological Institute of America (GIA), Carlsbad, California 92008, USA Both treated and synthetic gem materials are encountered today