Marinella is a Neapolitan brand, which was founded by Eugenio Marinella in 1914. It specialises in ties and other accessories. Marinella pocket squares are made in Italy. Their size is very generous – about 45*45 cm. (learn more about pocket square sizes here). Their edges are hand-rolled (but you can also find Marinella pocket squares with machine-rolled edges; maybe, those are fakes). The brand uses high quality 100% silk fabrics (printed in England). Colours and shades: blue, yellow, red, brown, cream, etc.
You can purchase Marinella pocket squares in Marinella boutiques (Milan, Naples, Tokyo, London, Lugano) and several multibrand stores (for example, Sartale in Vienna, St James in Moscow). Prices start at 80 EUR (incl. VAT). As far as I know, Marinella pocket squares are rarely put on sales, but you can find them on eBay or in some internet outlets. Beware of fakes.