A quick google found these facts…
Q: Can a rosary be worn as a piece of jewelry?
A: “Sacred objects, set aside for divine worship by dedication or blessing, are to be treated with reverence. They are not to be made over to secular or inappropriate use, even though they may belong to private persons” (CIC 1171).
Essentially, sacramentals such as rosaries must be treated with respect, particularly if they have been blessed. Reverence is the attitude of awe or respect that is most often given to sacred things. By its very definition, it is an interior disposition that usually cannot be determined by onlookers by appearances alone. A person may be wearing a rosary as a statement of faith, to keep it handy for praying throughout the day, or to avoid losing it. Those reasons would be indicative of reverence and would not interfere with the canon’s directive that sacramentals must be treated reverently.
Ordinarily speaking, then, if someone is spotted wearing a rosary, he should be charitably presumed to be wearing it for just reasons. Only if the rosary is being put to an objectively sordid use (e.g., a rock star is using it as a prop in a music video, obscenely contrasting the symbolic purity of the rosary with the immodest or immoral actions of the performers) can we be sure that the rosary is being treated irreverently.
catholic.com/thisrock/2004/0410qq.asp
A Plenary Indulgence…
may be gained (under the usual conditions) when the Rosary is prayed in Church, in a family group or in a religious community. Also:
Five (5) decades of the Rosary must be prayed continuously.
The prayers of the Rosary must be prayed vocally and one must meditate upon the Mysteries of the Rosary.
If the recitation of the Rosary is public, the Mysteries of the Rosary must be announced.
A Partial Indulgence…
One may gain a partial indulgence for the Rosary’s recitation in whole or in part in other circumstances.
A Plenary Indulgence…
can be gained only once a day (except by those who are in danger of death.)
- to gain a plenary indulgence one must perform the indulgenced act. Three other conditions must be fulfilled:
A sacramental confession
Eucharistic Communion
Prayers for the Pope’s intentions
In addition, one must be free of all attachments to sin, even venial sin. If this complete integrity is not present or if the above conditions are not fulfilled the indulgence is only partial. Both a plenary and partial indulgence may be applied to the dead.
themostholyrosary.com/indulgences.htm
The indulgences known as Apostolic or Apostolical are those which the Roman pontiff, the successor of the Prince of the Apostles, attaches to the crosses, crucifixes, chaplets, rosaries, images, and medals which he blesses, either with his own hand or by those to whom he has delegated this faculty.
newadvent.org/cathen/07788a.htm