Josef Marcolin (b 1933) and Benito Marcolin (b 1936), learned their glass making skills on the island of Murano, Venice, and later moved to Sweden to work at the Glimma glassworks in 1954, then Reijmyre 1956-61, before starting their own company, FM Konstglas. Several of the same designs can be found from both Reijmyre and FM Konstglas. FM stands for Färe-Marcolin, a combination of the brothers' surname and the maiden name of Josef's wife, Inga-Lill Färe (married in late 1950's). Inga-Lill's father Bror Färe was a businessman, and it is thought that he helped to fund the company, which would explain the inclusion of his surname in the company name. "Konstglas" is Swedish for "Art Glass". At first, they rented space at Eneryda glassworks. Glass produced while at Eneryda can be found with labels which read "FM Konstglas, Eneryda". They set up their own glassworks in 1961, in the Swedish town of Ronneby. Labels then read either "FM Konstglas, Ronneby" or "FM Konstglas, Ronneby, Sweden".
FM Konstglas / Marcolin pieces are often signed, including a pattern number, on the base, which consists of the initial of the designer, and model number of the item, sometimes followed by the size of the item. The size was given in millimetres up until 1983, when the size was instead given in centimetres, both in the signatures and price lists. Designer codes include: M - Josef Marcolin, B - Benito Marcolin, and F - Inga-Lill Färe. Production was mainly glass figurines, with a unique blended style of Swedish and Murano. They also produces other glassware such as vases, bowls and perfume bottles, using traditional Murano techniques such as millefiori, sommerso and zanfirico. These can easily be mistaken for Murano glass if not found with labels. The company changed its name to FM Marcolin Art Crystal in 1983, and in 1988-89 changed again to Marcolin Art Crystal. The Swedish factory closed in 1991, and production was moved to Sardinia, Italy, in collaboration with Sardinia Crystal, with the intention of producing the same products, however this didn't last long. The Marcolin brothers left and went their separate ways, Benito moved back to Sweden, while Josef moved to Austria and continued production under the name Marcolin Art Crystal. Update - Josef passed away in 2015, aged 82. The website for Marcolin Art Crystal no longer works, so it is possible the factory has now closed (needs confirmation).
Sources: Most of this information comes from a huge forum thread on FM Konstglas: [click here]. The forum is in Swedish, so like me you may find Google Translate helpful.