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Český granát - Bohemian Garnet
The precious jewels collection of Ulrike von Levetzow was thoroughly studied and restored. The collection consists of a multi-row necklace, paired bracelets, a ring, two earrings and a belt buckle stored in an original etui. Besides the high quality of manufacturing of all pieces, the main value consists in used materials. The collection was made of 469 pieces of unusually big Bohemian garnets (chrome pyropes), which were bigger than 8 mm. Usually, Bohemian garnets are smaller than 3mm. Moreover, the jewels were made of high purity gold (up to 22.5 carats) which was revealed by XRF analyses. The collection was deeply investigated. The gemmological survey was comprised of a study of inclusions and a refractive index, Raman and UV-VIS-NIR spectroscopy. All of the methods confirmed that the whole collection was made of Bohemian garnets from the Třebívlice area Central Bohemian Uplands. In pursuance of the restoration, it was necessary to make 7 new beads. First of all, we were searching for the most expedient technique to make new beads because the original manufacturing techniques are not known, or the tools were lost. Subsequently, many ways of drilling and cutting of garnets were tried and the best one was used for making of new beads. Of course, the etui was restored, as well.
Definice gemologických standardů českého granátu jako chromem bohatého pyropu. Popis vlastností, kterými je český granát charakterizován (index lomu, hustota, chování v UV záření, barva, obsah chromu, optické spektrum a inkluze). Pyrop, který tuto charakteristiku nesplňuje nemůže být označen za český granát. Definování těchto standardů je velmi důležité při rozlišování šperků, ve kterých je zasazen český granát od šperků, kde je zasazen pyrop z jiné produkční oblasti nebo dokonce jiný druh červeného granátů (většinou almandin) a tento šperk je nesprávně deklarován jako šperk s českým granátem. ----------------------------------------- Definition of gemological standards of Bohemian garnet as a chromium-rich pyrope. Description of the properties that characterize Bohemian garnet (refractive index, density, UV behaviour, colour, chromium content, optical spectrum and inclusions). A pyrope that does not have these characteristics cannot be designated as a Bohemian garnet. The definition of these standards is very important in distinguishing jewellery in which a Bohemian garnet is set from jewellery in which a pyrope from a different production area or even a different type of red garnet (usually almandine) is set and this jewellery is incorrectly declared as having a Bohemian garnet.