From the Order:

1. Marines will wear all ribbons to which they are entitled on service and dress "B" coats. Ribbons will be worn on the dress "A" coats only as authorized in paragraph 5202.  [only when no corresponding medal exists for an award ribbon]

2. When the blue dress "C/D" or service "B/C" uniforms are worn the wearing of ribbons on khaki shirts is at the individual's option unless the commander prescribes that ribbons be worn. If ribbons are worn on these uniforms, either all ribbons, or personal U.S. decorations with U.S. unit awards and the Good Conduct Medal, may be worn at the individual's option.

3. Ribbon bars will be worn on a bar or bars and pinned to the coat or shirt. No portion of the bar or pin will be visible.

4. Ribbon bars are normally worn in rows of three; however, rows of four may be worn when ribbon bars are worn in successively decreasing rows per subparagraph 5301.5. Female Marines may also wear two-ribbon rows when a three-ribbon row would not lay flat or would extend too close to the armhole seam.

5. When more than one row of ribbon bars is worn, all rows except the uppermost will contain the same number of ribbons. If the number of ribbons worn causes the ribbons to be concealed by the service coat lapel/khaki shirt collar (one-third or more of a ribbon concealed), ribbon bars will be placed in successively decreasing rows; e.g., four-ribbon rows, three-ribbon rows, two-ribbon rows, single ribbon. The left (outer) edge of all decreasing rows will be in line vertically; except the top row shall be centered over the row immediately below it.

6. Parallel rows of ribbon bars will either be spaced 1/8 inch apart or placed together without spacing at the individual's option.

7. Ribbon bars will be centered 1/8 inch above and parallel to the top edge of the upper left pocket of dress "B" coats, service coats, and men's khaki shirts. When marksmanship badges are worn, ribbon bars will be centered over the pocket with the bottom edge of the ribbon bar 1/8 inch above the widest holding bar of the marksmanship badge(s).

8. On women's coats with horizontal pockets, ribbons will be worn as prescribed above. On women's coats with slanted upper pockets, a horizontal line tangent to the highest point of the pocket will be considered the top of the pocket (see fig. 4-3). On women's khaki shirts, ribbon bars will be placed even with or up to 2 inches above or 1/2 inch below the first visible button and centered so that they are in about the same position as when worn on the coat. On coats without the faux pocket, ribbon bars will be placed on a horizontal line with the bottom edge of the ribbon bar 1 1/2 to 3 1/2 inches above the first visible coat button and centered so that they are in about the same position as when worn on the shirt. On the maternity tunic, ribbon bars will be placed so that they are in about the same position as when worn on the service coats. On the khaki maternity shirt, when worn as an outer garment, ribbon bars will be worn in the same manner as on the standard khaki shirt and may be adjusted to the individual to present a military appearance.

GENERAL
1. Ribbons for ribbon bars will be of the same material as the medal's suspension ribbon. Ribbon bars authorized for awards that have no medal such as the Presidential Unit Citation, Navy Unit Commendation, etc., will be of the material prescribed in applicable military specifications.

2. Each U.S. ribbon bar will be 3/8 inch high and 1 3/8 inch wide (same as the width of the medal's suspension ribbon). Foreign ribbon bars (including those with devices) that have been authorized for wear by CMC (MMMA) may be worn only if they can be adapted to meet regulation height requirement and do not exceed twice the width of the standard U.S. ribbon bar. When stacking ribbons (with a 1/8 inch gap between the rows), the part of ribbon bar connecting the rows should be inconspicuous or clear in color.

3. Ribbon bars will not be impregnated with preservatives which change the appearance of the ribbon, nor will they be worn with any type of transparent coverings.

4. Ribbons bonded to a plastic backing instead of a metal bar are approved for wear at the option of the individual. These ribbon bars lie flatter than the standard ribbon bars and may include magnetic fasteners in lieu of clutches for attaching to the uniform. These ribbon bars will bear Marine Corps approval identification.
5. Stars and other attachments will be worn as prescribed in section 4 of this chapter.