Deterioration phenomena of various types of commercial pearls were classified into the following categories, and their mechanisms, changes over time, prevention and reparability were examined.
(1) Processing flaws
(2) Layer separation and flaking
(3) Cracking and breaking cause of the prismatic layer
(4) Color fading and changing
(5) Surface dissolution

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This is the first study that examined the feasibility of objective measurement of the TERI of pearls.
First, Akoya pearls were classified based on three interference color patterns. Next, their expression intensities were classified into seven scales based on visual observation by experts. Then, correspondence of these scales to reflective interference light categories determined by an aurora viewer and to TERI values measured by Teri measuring instrument was examined.

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It is known that the conch pearl of a natural "pink shell" has the intersection board structure unlike the pearl with usual nacre. The similar appearance with the conch pearl, so called "fake", which is made by grinded "pink shell", (the mother of shell of the conch pearl) is often found in the market probably because the conch pearl is very valued for its rarity. This time, we considered the different points between the conch pearl and the imitation pearl from the surface observation. Also, we cut and grinded different parts of "pink shell" by ourselves and tried to verify the variety of this imitation pearls.
As it was reported by "Succeeded in cultivating the conch pearl" in November, 2009 , the soft X-rays penetration inspection came to have the key role in the inspection of the conch pearl. We would like to point out some issues on this matter.

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[in Japanese]

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"Trapiche" is a word taken from a Spanish "trapicho", the gear of the sugar cane crushing apparatus. Trapiche crystals were reported on emerald, corundum (ruby and sapphire), tourmaline and spinel, which show the texture of six arms and surrounding six growth sectors resembling trapicho. We reported new trapiche-type crystal, a trapiche quartz.
Pale-yellow quartz crystals from Goyomatsu mine (contact metasomatic deposit), Nara Prefecture, Japan have the dendritic inclusion elongated parallel to the c-axis. Such a texture has never been observed in quartz crystal and is different from so-called faden quartz. In the c-cut plate, six dendritic arms in the central portion and the surrounding growth sectors are observed. A lot of voids are seen between dendrite and surrounding sectors. Electron probe micro analysis and X-ray diffraction experiments identified the central dendritic portion to be a quartz. Cathodoluminescence tomographs show the following texture. (1) The growth zoning parallel to the prism face occupied the major portion of the surrounding growth sectors, (2) the growth zoning parallel to the pyramidal faces were seen only as thin layers under the face.
These growth features indicate that the quartz crystals were formed through two growth stages: (1) Quartz dendrites grew at first under high supersaturation condition, (2) followed by changing the growth condition, the surrounding growth sectors grew under lower supersaturation condition around the quartz dendrite, which worked as seed crystals. This processes resulted in an unusual texture of quartz crystals, a trapiche quartz.

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Rhodochrosite from Inakuraishi Mine, Hokkaido, Japan is one of the most beautiful gemstone from Japan. We compared it with other rhodochrosite from other origins including Oregon USA, Argentina, Chile, South Africa, Brazil, Russia and China. Those from Hokkaido show distinct features of chemical composition of trace element. Other features of UV-Vis and FT-IR spectrum are also shown.

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Matara district and Hambantota district in southern Sri Lanka are major localities of Hessonite Garnets.
Two mines are approximately 60 km away from each other, so that those Garnets are shown different colors.
I would like to introduce gemological properties of both materials including locality information.
And next, I would like to introduce following gem materials I had identified recently.
(1) Vayrynenite from Pakistan
(2) Amphibole in Apatite from Pakistan
(3) Lazulite in Scapolite from Afghanistan

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We tested of high temperature (1400° and 1700°) treatment on spinels. The purple spinel changed to dark but light green with 1700° heating. Other color also became dark. The absorption rose in all spectrum but especially higher in violet to blue and less green. This change of absorption gives yellowish and dark color to spinels.

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[in Japanese]

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[in Japanese]

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It is able to identify gem using X-ray powder diffraction pattern of approximately 4,600 species of the database of minerals. This method require pulverized gem.
Gem has to avoid destructive testing.
On the other hand X-ray micro-diffraction is widely known as an analytical instrument without the need for powder.
X-ray micro-diffraction will contribute in the gemmology.

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[in Japanese]

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[in Japanese]

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1) From in-situ observation and analysis of Congo diamond, it contains nano-particles of carbonates (including calcite) and gypsum, together with halite of clear crystal plane and grains of Fe-silicates(without Mg) covered wholly by irregular carbon-bearing grains.
2) Kimberley diamond of South Africa shows different grains of Ca,Mg,Fe and Ti -bearing carbonates (without halite in composition).
3) From other data of diamond texture, Congo diamond is considered to be formed at shallow place by discarding previous history.

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