It shall be unlawful to advertise in newspaper or by sign, handbill, placard, or otherwise, the price at which eggs are offered for sale without plainly indicating in conjunction with price, the full and correct designation of grade, size of the eggs according to the standards in this chapter, of geographic origin of eggs, and of shell treatment if applicable. The designations shall be in a typeface or other conspicuous letters as provided in the rules of the department of agriculture.