Some bottles feature popular characters like Mickey Mouse. Round bottles were the earliest containers, but most companies changed to a square shape around 1950. But both shapes and many sizes are worth money to collectors. A few bottles have bulbous necks to trap the cream.
Most colored bottles are valuable.
Many blue bottles are usually cheap reproductions, however. The Holy Grail of milk bottles is a 1950 ruby red bottle from Borden. Remember only bottles in perfect condition are sought. If your bottle has cracks, bad chips, stains or paint worn off one or both sides, it can go straight to the recycling bin. For more on collectible milk bottles, Hyman recommends Ralph Riovo, a long-time collector.