“Diamond I” or “I inside a Diamond” mark seen on antique bottles

Typical "generic" amber "packer" bottle made by Illinois Glass Company, marked with "Diamond I" on base.

Typical “generic” amber “packer” bottle made by Illinois Glass Company, marked with “Diamond I” on base.

Mark on bottom of amber bottle made by Illinois Glass Company.

Mark on bottom of amber bottle made by Illinois Glass Company.


“Diamond I”  or  “I inside a Diamond” mark seen on Antique Bottles

Illinois Glass Company, Alton, Illinois (1873-1929)

(This particular mark used circa 1915-1929)

The Illinois Glass Company was incorporated at Alton, Illinois in March of 1873.   During the earlier years, many of their bottles carried an “I. G. CO.” mark, and later an “I G CO inside a diamond” logo. See more info on those marks on Page Three.

This Diamond/I mark was used by Illinois Glass from approximately 1915 up to 1929, and is seen on many antique and vintage glass bottles.   ABM (Automatic bottle machine) production was begun at Illinois Glass in 1910, and although it seems more likely (to me) the “I in a diamond” trademark would have been first used around that time,  the U.S. Patent & Trademark Office data indicates Illinois Glass Company actually claimed use of this particular trademark was begun in 1915.

Although there is probably no way to prove it, I suspect that some bottles made between 1910 and 1915 also carry the “Diamond/I” mark.   Perhaps someday more info will come to light to show the very earliest use of this mark!

Diamond-I mark

Diamond-I mark

The “I in a diamond” mark is seen on HUGE numbers of containers.   The great majority of these bottles were made in clear glass, with a smaller percentage found in amber glass, light aqua,  or occasionally cobalt blue.  Some bottles made originally in clear glass may turn a faint amethyst shade from sun exposure. Darker shades of purple indicate the glass color has been altered in recent years via irradiation. (Please see this page on irradiated bottles or “artificially purpled glass“) . No Illinois Glass Company bottles were ever made originally in dark purple glass!

Small generic medicine/pill bottle made by Illinois Glass Company, bearing the "I inside a Diamond" mark on the bottom

Small generic medicine/pill bottle made by Illinois Glass Company, bearing the “I inside a Diamond” mark on the bottom

Many, many hundreds (if not thousands) of types / styles of bottles are known.  Many of them were standard “packer ware” or “generic” types, used for a multitude of different products………. medicines, foods, sauces, extracts, flavorings, chemicals, bleach, vinegar, cosmetics, etc………….. the end user company would have pasted their own private brand label on the side with a description of the contents.   Often there would be no embossed markings on the bottle other than the logo seen on the very bottom.

Many of these bottles are found in old trash dump sites,  privy pits (underground, where an old outhouse once stood),  and anywhere old farmsteads were located.

As far as I know, the “I inside a diamond” mark is only seen on machine-made bottles (perhaps with the exceptions of some very large hand-blown bottles, or special-order, limited-production items) which exhibit the typical Owens machine suction scars on the base.  The “Owens scar” is a more or less circular, thin “seam”, “line” or discontinuity in the surface of the glass, visible around the perimeter of the bottom of the bottle produced by those particular machines: the Owens Automatic Bottle machines. The scar can have a vaguely “jagged” appearance.

Typically, the “I” is discernible within the diamond, but on very small bottles it may be indistinct, incomplete, distorted or “smeared” in appearance.  Sometimes the “strike” or “impression” is so light that the mark can just barely be seen, and then only on close examination under a bright light shone at an angle.

In some cases the steel mold might have had dirt, debris or graphite buildup filling in the engraving (incising), resulting in a “missing I” on the finished bottle.  In some cases, a bottle with just a plain diamond (no “I”) MIGHT be a product of the Diamond Glass Company, of Royersford, Pennsylvania.  In some of these cases it is (to be honest) not certain which company was the maker.

The “I” is sometimes misinterpreted as the “number 1”, and often does looks quite like a  numeral “one” on some examples.    On some very small bottles, the “I” may look more like a raised period (dot) inside the diamond, or be entirely missing.

Occasionally you may run across a bottle with what is called “ghost embossing” (a double impression, or faint repetition of the mark).  This is seen often on glass electrical insulators.  This phenomena occurs when the (molten) glass shifts very slightly after reaching the inside surface of the mold, (picking up an impression of the mark), and a split second later settles into it’s ‘final resting place’ inside the mold, leaving a double “strike” of the raised embossing .

"766" inside a diamond - mark on the base of a small "generic" light aqua bottle made by Illinois Glass Company.

“766” inside a diamond – mark on the base of a small “generic” light aqua bottle made by Illinois Glass Company. This identified the bottle as their “No 766” mold in bottle catalogs and/or communications with buyers.

There are also many bottles known with a number or number/letter combination within a diamond. These are also products of Illinois Glass Company, and some of the these numbers have been matched up with bottle style listings in early trade catalogs published by Illinois.

The name “LYRIC” was used by Illinois also, and this is a brand name they assigned to a line of pharmaceutical (prescription) bottles, and is often seen on the base of those types of bottles.  In many cases, the diamond mark is embossed along with “LYRIC”. See this page on the LYRIC bottles.

I. G. CO. had a very large manufacturing facility at Alton,  IL, with over a thousand employees working there during the heyday of their operation.

Other glass manufacturing plants that were purchased by, and became part of Illinois Glass Company during its operation include the Thompson Bottle Company of Gas City, Indiana (acquired 1913) ;  Chicago Heights Glass Company, Chicago Heights, Illinois (1913) , and Cumberland Glass Manufacturing Company of Bridgeton, New Jersey (1920).

Illinois-Pacific Glass Co. plants (at Los Angeles and San Francisco, CA) were organized as a wholly owned subsidiary of Illinois Glass in 1902.  (See IPG and IPGCO marks on this page.)

In 1929, Illinois Glass merged with Owens Bottle Company of Toledo, Ohio to form the Owens-Illinois Glass Company.   Owens Bottle Company produced tremendous numbers of bottles, jars and other containers with the “O inside a square” or “Squared O” mark which is also frequently seen on bottles from the 1920s.

The Alton factory (in later years, Owens-Illinois plant #7)  finally closed in 1983.

NOTE: this mark (especially when the I has very prominent serifs or “crossbars”) is sometimes confused with an “H in a diamond” mark which was used by the Heisey Glass Company (A H. Heisey & Company, Newark, Ohio, 1896-1957).  The Heisey mark is seen only on high quality pressed glassware, elegant pattern glass tableware, etc.,  not on utilitarian and commercial-type bottles which was the mainstay of Illinois Glass production.

For more in-depth information on Illinois Glass Company, its history, and the various identification marks they used, check out this article (by Bill Lockhart, et al) at: The Dating Game: Illinois Glass Company.

A great resource for learning more about Illinois Glass Company containers (and older utilitarian-type glass bottles in general) would be this webpage (hosted by Bill Lindsey) with links to pages from an original 1920 Illinois Glass Company bottle catalog: http://www.sha.org/bottle/igco1920.htm” .   Clicking on the links on that page will bring up photographs of individual catalog pages with drawings illustrating many of the designs sold by Illinois, including “standard” and “generic” packers and many other types. Most, if not all, of the containers shown were marked on the base with the Diamond-I trademark. The typical “bottle type terminology” used by glass manufacturers of that period will be a help to archaeologists, collectors or anyone interested in antique bottles from the early 20th century. There are also other Illinois Glass Co. catalogs shown on the site including one circa 1906: http://www.sha.org/bottle/igco_1906.htm .

Please click here to go to my Home Page.

Click here to go to the Glass Bottle Marks pages (page one).

Check out my summary page on Sea Glass / Beach Glass. Sometimes Illinois Glass Company bottle bases are found among so-called “Beach Glass.”


2 Responses to “Diamond I” or “I inside a Diamond” mark seen on antique bottles

  1. Raina says:

    this one is an i believe 100cc bottle number 4 in a circle on neck followed by scroll things down towards the numbers. on the left side = is numbers 3, 2, and 1. on the right side = 80, 60, 40, 20, cc. opposite side of bottle is an empty circle on the neck, followed by same scrolls. finally the bottom is a large circle with ILLINOIS 11 a diamond shape with an i inside of a large O.