The following is drawn from the Dr. John Schmale's now defunct web site and my two visits in 1994 and 1995 to the Hall of Flags in the Centennial Building in Springfield IL. This was before the Illinois flags were all moved into storage at the Illinois National Guard's Camp Lincoln in 2003.
The 9th Illinois has two surviving national colours. The first was presented to the regiment in June 1861. It has 34 stars arranged in a shield shape in the canton. The second national colour appears to be made by Tiffany & Co. Tiffany national colours had a square canton with 34 gold stars arranged in six horizontal rows 6-6-5-5-6-6. The unit designation was embroidered on the fourth red strip in either block printing or more commonly in a flowing script.
The 9th Illinois also had at least two regimental colours. The first was presented to the regiment in June 1861. The Belleville Weekly Advocate described this flag as follows:
"The flag is composed of a field of rich blue silk in the centre of which is embroidered the armorial device which constitutes the obverse of the great seal of the United States; consisting of a shield of thirteen stripes upon the breast of the American Eagle, displayed holding in his beak a scroll of white satin, inscribed with the motto 'E PLURIBUS UNUM'; in his dexter talons an olive branch and in his sinister a cluster of thirteen arrows. Over the head of the eagle is a cluster of thirteen stars in the form of a semi-circle, and in his talon is also held a scroll on the obverse of which appears the motto: 'Illinois U. S. Volunteers'; and on the reverse: 'Return Victorious'. The eagle is embroidered in gray silk, and the stars and mottoes are worked in gold; all in the most skillful manner."
The 9th Illinois' second regimental colour is identifiable as a New York Depot flag.
The 12th Illinois was issued a Cincinnati Depot National Colour with non-regulation red and white cords. Cincinnati Depot national flags had white stars in the canton arranged in seven horizontal rows of 5-5-5-5-5-5-4 stars.
It also was provided with a New York Depot regimental flag.
The 12th Illinois also was presented with a unique regimental flag described, along with the above flag, in the 27 November 1861 Louisville Daily Journal as follows.
"The regimental color is composed of blue silk, regulation size, finest texture, fringed with yellow in the centre of which was a gilt spread-eagle from the beak of which floated a ribbon upon which were inscribed the words, ‘E Pluribus Unum'; the eagle was encircled with thirteen stars over which in a half circle appeared a rich halo and underneath the eagle in gilt letters were the words ‘12th Reg. Ill. Volunteers'. The other flag was of white silk with red border and yellow fringe ornamented in the centre with a representation of the Scotch thistle, over and beneath which were inscribed the following familiar words (with the exception of McArthur's name being substituted for that of the hero of Lucknow), ‘Dinna ye hear the slogan? Tis McArthur and his men!'"