A packaging system, comprising: - a container, which includes a neck defining an axis (X-X), and - a stopper for closing the neck, which includes a skirt provided with first threading means for removable fastening around the neck, adapted to cooperate with second threading means borne by the neck so as, by applying a preset stress for having the first fastening means cooperate with the second fastening means, to have the packaging system pass from an open configuration, in which the stopper is at least partially freed from the neck to open the neck on the outside of the container, to a closed configuration, in which the skirt occupies at least one predetermined position on the neck in which the stopper seals the neck, the stopper being open at its lower end and closed at its upper end by a bottom wall, wherein the skirt includes two tubular axial parts, centered on the axis (X-X) and successively in the direction of the axis (X-X), a lower skirt portion and an upper skirt portion which connect the lower skirt portion to the bottom wall, the inner surface of the lower skirt portion being provided with a raised portion which protrudes radially inward and is adapted to abut axially upward against an outer heel of the neck when stopper is opened for the first time, so as to axially retain the lower skirt portion around the neck, subject to the breaking of a peripheral weakening line initially connecting the lower axial end of the upper skirt portion and the upper axial end of the lower skirt portion to each other, the packaging system including checking means (20, 21, 22, 23) for visually checking that the packaging system is in said closed configuration after applying said preset stress; characterized in that, said checking means comprise both: - first indicators (20, 22) of the angular position around the axis (X-X) between the neck and the skirt, said first indicators being respectively borne by the neck and the skirt and being designed to be arranged with an angular spacing between them which is smaller than a first predetermined value when the packaging system is in said closed configuration, the first indicator, borne by the neck is in the form of an elongate rib that extends in the direction of the axis (X-X) and the first indicator, borne by the skirt, being in the form of a rib that protrudes from the outer surface of the skirt and assuming an elongated rib shape extending in the direction of the axis (X-X) when the packaging system is in its closed configuration, the first indicator, borne by the skirt, being situated in the lower skirt portion and - second indicators (21, 23) of the position along the axis (X-X) between the neck and the skirt, said second indicators being separate from the first indicators (20, 22), borne respectively by the neck and by the skirt, the second indicator borne by the neck, is in the form of an elongate rib that extends in the direction orthoradial to the axis (X-X) and indicator borne by the skirt coincides with the lower end of the stopper, the second indicator being designed to be arranged parallel to each other with an axial spacing (Δ) between them which is below a second predetermined value, when the packaging system is in said closed configuration. - a container, which includes a neck defining an axis (X-X), and - a stopper for closing the neck, which includes a skirt provided with first threading means for removable fastening around the neck, adapted to cooperate with second threading means borne by the neck so as, by applying a preset stress for having the first fastening means cooperate with the second fastening means, to have the packaging system pass from an open configuration, in which the stopper is at least partially freed from the neck to open the neck on the outside of the container, to a closed configuration, in which the skirt occupies at least one predetermined position on the neck in which the stopper seals the neck, the stopper being open at its lower end and closed at its upper end by a bottom wall, - first indicators (20, 22) of the angular position around the axis (X-X) between the neck and the skirt, said first indicators being respectively borne by the neck and the skirt and being designed to be arranged with an angular spacing between them which is smaller than a first predetermined value when the packaging system is in said closed configuration, the first indicator, borne by the neck is in the form of an elongate rib that extends in the direction of the axis (X-X) and the first indicator, borne by the skirt, being in the form of a rib that protrudes from the outer surface of the skirt and assuming an elongated rib shape extending in the direction of the axis (X-X) when the packaging system is in its closed configuration, the first indicator, borne by the skirt, being situated in the lower skirt portion and - second indicators (21, 23) of the position along the axis (X-X) between the neck and the skirt, said second indicators being separate from the first indicators (20, 22), borne respectively by the neck and by the skirt, the second indicator borne by the neck, is in the form of an elongate rib that extends in the direction orthoradial to the axis (X-X) and indicator borne by the skirt coincides with the lower end of the stopper, the second indicator being designed to be arranged parallel to each other with an axial spacing (Δ) between them which is below a second predetermined value, when the packaging system is in said closed configuration.