(815 ILCS 395/5) (from Ch. 121 1/2, par. 142)
    Sec. 5. There shall not be applied to any article any quality mark nor any colorable imitation thereof, nor any contraction thereof, nor any addition thereto, nor any words or letters, nor any mark purporting to be or resembling a quality mark, except as follows:
    (1) An article consisting of at least 985/1000ths parts of platinum, iridium, palladium, ruthenium, rhodium, and/or osmium, where solder is not used and at least 950/1000ths parts of said same metal or metals where solder is used, may be marked "platinum": Provided, that the total of the aforementioned metals other than pure platinum shall amount to no more than 50/1000ths parts of the contents of the entire article.
    (2) An article consisting of at least 985/1000ths parts of platinum, iridium, palladium, ruthenium, rhodium, and/or osmium, where solder is not used and at least 950/1000ths parts of the said same metal or metals where solder is used: Provided, that at least 750/1000ths parts of said article are pure platinum, may be marked "platinum": Provided further, that immediately preceding the mark "platinum" there is marked the name or abbreviation as hereinafter provided, of either iridium, palladium, ruthenium, rhodium, and/or osmium, whichever of said metals predominates: And provided further, that such predominating other metal must be more than 50/1000ths parts of the entire article.
    (3) An article consisting of at least 985/1000ths parts of platinum, iridium, palladium, ruthenium, rhodium, and/or osmium, where solder is not used and at least 950/1000ths parts of said same metals where solder is used: Provided, that more than 500/1000ths parts of said article consists of pure platinum, may be marked with the word "platinum": Provided further, that said word is immediately preceded by a decimal fraction in one-thousandths showing the platinum content in proportion to the content of the entire article: And provided further, that said mark "platinum" be followed by the name or abbreviation as herein allowed, of such one or more of the following metals, to-wit: Iridium, palladium, ruthenium, rhodium, and/or osmium, that may be present in the article in quantity of more than 50/1000ths parts of the entire article. The name of such other metal or metals other than platinum, however, shall each be immediately preceded by a decimal fraction in one-thousandths showing the contents of such other metal or metals in proportion to the entire article--as, for example, 600 Plat., 350 Pall., or 500 Plat., 200 Pall., or 150 Ruth., 100 Rhod.
    (4) An article consisting of 950/1000ths parts of the following metals: Platinum, iridium, palladium, ruthenium, rhodium, and/or osmium, with less than 500/1000ths parts of the entire article consisting of pure platinum, may be marked with the name iridium, palladium, ruthenium, rhodium, and/or osmium, whichever predominates in the said article, but in no event with the mark "platinum": Provided, however, that the quantity of such metal other than platinum so marked must be marked in decimal thousandths: And provided further, that the name of such metal other than platinum so used must be spelled out in full, irrespective of any other provisions of this Act to the contrary.
    (5) An article composed of platinum and gold which resembles, appears, or purports to be platinum may be marked with a karat mark and the platinum mark provided:
    (a) The platinum in such article shall be at least 985/1000ths parts pure platinum; and
    (b) The fineness of the gold in such article shall be correctly described by the karat mark of said gold; and
    (c) The percentage of platinum in such article shall be no less than 5 per centum in weight of the total weight of the article; and
    (d) The mark shall be so applied that the karat mark shall immediately precede the platinum mark, as, for example, "14 K & Plat.," "18 K & Plat.," as the case may be, it being expressly provided that in case the percentage of platinum exceeds the 5 per centum provided herein the quality mark may also include a declaration of the percentage of platinum, as, for example, "18 K & 1/10th Plat.," or "14 K & 1/8th Plat.," or as the case may be.
    (6) An article composed of platinum, and any other material or metal not resembling, appearing, or purporting to be platinum, may be marked with the quality mark platinum: Provided, that all parts or portions of such article resembling, or appearing, or purporting to be platinum, or reasonably purporting to be described as platinum by said quality mark, shall be at least 985/1000ths parts pure platinum.
(Source: Laws 1927, p. 783.)