Jensen silver represents a good investment for the collector, but there are a number of variables that need to be taken into consideration so that you don't end up buying the wrong thing.

Firstly, always be careful about anything marked 'Georg Jensen Inc'.  These pieces were made in the USA during the post-war period when the New York shop tried to pinch the Georg Jensen trademark - they have never been near Denmark and were either copied from existing Jensen designs or were designed and made 'in the style of'. Either way, they were manufactured by silversmiths in the USA and not by Georg Jensen.

Although still collectable in their own right, they are typically of poorer quality than the real thing and realise much lower prices at auction. But they still represent an interesting area of collecting for those on a budget.

For the avoidance of doubt, with the exception of some very recent jewellery production which has been outsourced to Malaysia, all Jensen silver has been produced in the smithy in Copenhagen, Denmark.

 We are also seeing an increased number of pewter pieces on eBay, purporting to be made by, originating from, or designed by the Jensen smithy. For the record, Jensen has never produced in anything but silver or gold (except for the incorporation of iron during the war years by designers such as Malinowski).  The surname Jensen is the equivalent of Smith in Denmark, so be wary of any claims that a maker is directly related to him!  There is at least one pewter manufacturer - Jorgen Jensen - who did at one time work in the Jensen smithy, but who, despite claims, is not related to the man himself and his work is of little value, especially given the medium.

Date markings are often an area of confusion. The standard marks are well documented, with the exception of one; a plain 'sans serif' GI which dates to the early 1930s (and not the early 1900s as many sellers will often claim - the GI used then was either 'serif' i.e. simply put, it had twiddly bits on the letters, and was often intertwined, or was plain, i.e. sans serif, but surrounded by a circle of dots).  The GI mark I speak of always appears simply as two plain letters, with no decoration or encircling.

You will also see contradictions in terms of silver grade and date mark.  Jensen started out using 826 and subsequently 830 grade silver which did not attract as much tax as the purer and more widely used european standard of 925, but they progressively moved to the 925 standard during the 1920s. Perversely, largely because it is the oldest output from the factory, but also because it has a noticeably nicer, warmer colour, this lower grade silver, while technically less valuable in pure scrap terms, is usually much more desirable to the collector.

You may often see pieces with a later date letter (I've seen as late as the 1933-44 mark with a UK hallmark fairly late in that period) carrying an earlier 830 silver grade stamp.  This arose because the smithy (and remember, as unromantic as it seems, it was a factory, not an artistic community per se) used to make components in batches, but not all of them would be used when they did a production run of a specific item, say a necklace.

The remainder would be left in a drawer or cupboard somewhere, often only resurfacing after many years when they would be incorporated into the next production run. So it was simply a legal requirement that the factory had to stamp the piece to indicate that some or all components were made of a lesser silver grade than what was by then a truly european-wide standard of 925, but they would still carry the correct date of assembly for the item itself (Jensen pieces often consist of a surprisingly large number of individual components!).

On the other side of the coin, the 925 stamp is also a good guide.  For example, where sellers claim the GI mark noted above to be 'from the early 1900s', the presence of a 925 stamp will affirm its actual manufacturing date to be later than the early 1920s....in the case of the 'sans serif' GI mark, this would be 1930s as mentioned (exact start and end dates for this mark are unclear but it was apparently only used for 2-3 years).

You will also sometimes see what seems to be an actual date, e.g. 1919 or 1920, in a stamped box on a few pieces.  This is exactly what it appears to be and was a device used by the factory occasionally during the very early years, so don't be put off by its appearance.

Finally, if you are lucky, you may see a piece that carries the mark 'GJ Ld' and a UK silver hallmark, in addition to the factory markings.  The first simply means that it was imported by Georg Jensen Limited, the Bond Street store (now relocated I believe), while the hallmark letter will tell you exactly what year it was imported, which will normally be fairly soon after its manufacture.  It has also proven a useful marker when viewing pieces with apparently contradictory factory markings, since the UK hallmarking system is, unlike many parts of the world, rigorously and strictly enforced.

Don't be misled, though, by sellers who will sometimes encourage you to think that the GJ Ld hallmark alone is of any value.  Like most silver retailers, the GJ shop (which remember is effectively little more than a franchise) also sells other non-Jensen items of silver which it 'commissions', i.e. usually buys in bulk, which are normally stamped with the mark of the retailer, in this case the Jensen store.  Remember, if it doesn't have a set of Georg Jensen Danish factory marks, which usually include the relevant Jensen logo for the period (all well documented on the internet), the words 'Sterling' and 'Denmark' and a design number, then it isn't Georg Jensen.  There are a very small number of exceptions, but most of them will be present in one form or another.

And if you're buying a post-1945 item, its often very difficult to date accurately, especially if there is no UK or other hallmark, but if you look for pieces with tiny gas holes on the reverse (you'll see what I mean when you find them; they are there to prevent the piece from expanding and distorting when two halves - usually front and rear - are soldered together before finishing) - they are usually vintage as opposed to later.

Hope this all helped.....

Happy Hunting!