The agency is to build engagement and awareness of platinum, and convince the public to consider it an affordable luxury option.
A media relations campaign will involve promoting top platinum jewellery designers and their latest collections to UK media.
The retained brief was won following a four-way pitch.
PGI was founded in 1975 in London. It provides sales support and training to all levels of the jewellery trade, and is funded by platinum producers and refineries.
PGI UK manager Ruth Donaldson said: ‘We are passionate about inspiring jewellery buyers to choose platinum and the UK will be a key focus for us in terms of events and consumer activity this year. Euro RSCG London PR demonstrated the perfect blend of creativity and understanding of what we were looking for on this campaign.’
Commenting on the appointment, Euro RSCG London account director Helen Doyle said: ‘Platinum Guild International is a fantastic addition to our luxury portfolio. One of our key goals will be to communicate the clear benefits of platinum for consumers over gold or silver.’