The Chivas brothers started selling Scotch whiskey in the U.K. at the beginning of the 19th century. In the U.S., Chivas Regal launched a 25-year-old blend of whiskey in 1909. This was sold until the Prohibition era -- 1920 to 1933 -- then disappeared. Bottles of Chivas Regal from this time are collector's items. A Chivas Regal bottle's age can be identified by using bottle characteristics, label information, and by the presence of a tax stamp.
Look at the bottle for clues as to how it was made. Bottles made prior to the late 1800s were blown and have a pontil mark. A pontil -- or punty -- is an iron or steel rod that enables blowers to handle hot glass. When the bottle was completed, the rod was broken off, which left a sharp piece at the center bottom of the bottle. After this, molds were used to shape glass into bottles. An early-1900s bottle has a smooth base -- no pontil -- and a seam line. The seam line stops part way up the neck of the bottle. Bottle lips were applied after the bottle was molded, and the lips were ground smooth. Modern bottles have screw tops and well-formed bodies and lips.
Study the label of the Chivas Regal bottle in your possession. The amount of wear on the paper label as well as on the bottle itself can be indicative of its age. The oldest Chivas Regal bottles sold in the United States would have been between 1909 and 1920. Chivas Regal 12 was sold beginning in the early 1950s and is still sold today. In 1997, a new blend, Chivas Regal 18 Gold Signature was introduced, and may still be found for sale today. Chivas Regal 25 returned in limited release in 2007.
Look for a paper tax stamp or strip on the bottle. Liquor, like tobacco, is included in a list of sin-tax items. The tax money was collected by the Internal Revenue Service, and the stamps showed that the tax had been paid. Some stamps were paper strips that went over the top of the bottle and down the neck. Some were smaller and placed on the body near the neck. These stamps were used until 1985.
Take the information you have collected -- the bottle's characteristics, label information, and tax-stamp information -- and formulate a theory as to the bottle's age. For example, a bottle with a seam line all the way up the neck will give you a range circa 1930 to the present day. A label with the Chivas Regal 12 logo, means the whiskey was distilled into that bottle no earlier than 1950. If there is a tax stamp, your bottle may have been sold as late as 1985. On the other hand, if your bottle has a ground lip and a partial seam line, along with the label indicating Chivas Regal 25 -- with or without a tax stamp -- your bottle is likely from the early 1900s.