Daily useful information
During one day's work, many different on-line sources may be useful. Here goes the links that were useful to me! Let me know yours, especially if some of them are specific to your job or country!
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Let's start with important data to keep in mind:
1 carat (ct) = 0,2 gram (g)
1 gram (g) = 5 carats (ct)
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Some US companies, like auction houses, may give you the gross weight in pennyweights (dwt).
1 pennyweight (dwt) = 1.55517384 gram (g)
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Converters
Converter from grams to carat: Metric Conversion
Old currency converter: here
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Metal rates
Metal rate €urope: Cookson-CLAL
Metal rate in Dollar$ : Kitco
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Translation
On-line very efficient translator: DeepL Translator
You may also use Chat GPT, but please be careful what data you are feeding it. It would be ill-advised to have him translate strategic data for example.
One must however be very careful and always have a native person proofread the document that you have translated with an on-line translator, specifically if it tackles technical subjects (manufacturing, contracts, etc.)
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Hallmarks & Research
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The official website published by the Ministry of Culture, for French marks: la plateforme ouverte du patrimoine
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Research Jewel : a very thorough website created by Vanessa Cron (yearly fee charged but you may test it for 24h for free)
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On-line encyclopedia of Silver Marks, Hallmarks & Makers' Mark (free of charge)
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Gold Hallmark Identification Wizard by Gold Traders, a UK based research tool (free of charge).
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​Many interesting books that are no longer published today are still available, such as the French 'Guide Bijou', which can prove invaluable and a number of experts in the trade are able to carry out research, sometimes personnifying why I call the "Indiana Jones of the hallmark".
Also noteworthy, the École des Arts Joailliers published at the end of 2021 in partnership with Gallimard a reference work for professionals and amateurs of goldsmiths and jewellers: the Dictionnaire des joailliers, bijoutiers et orfèvres en France, de 1850 à nos jours. Sold at a price of €650 including tax, it can also be consulted at the School's library upon reservation or at the Union Syndicale, upon request. Unfortunately it is not available in English.
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Your research are about coins ? Check your information there: Cosmos of Collectibles