The mark you describe sounds like the mark Imperial Glass Corporation used from 1951 - 1972. It is the letter G over the letter I but it looks like an arrow to me. Google image the mark to see if it's the one you mean.
Imperial Glass was founded in 1901 as New Crystal Glass but quickly changed to Imperial Glass. It was founded by Edward Muhlemon in Belaire, Ohio. During the early part of the 20th century, they made products for Woolworth's. They produced Carnival glass beginning in 1909. Later, they made imitation cut glass and art glass. They became Imperial Glass Corporation in 1931 creating Elegant glass as well as the famous Candlewick pattern. The company began to reissue old patterns in the 1960s and went out of business in 1984.