In the present day, precious stones having soared far out of reach of all but the really rich, fashion rather prefers a large semi-precious one to a microscopic diamond. "Fashion," however, is merely momentary and local, and the great majority will probably always consider a diamond the only ring to have.
It is not obligatory, or even customary, for the girl to give the man an engagement present, but there is no impropriety in her doing so if she wants to, and any of the following articles would be suitable: A pair of cuff links, or waistcoat buttons, or a watch chain, or a key chain, or a cigarette case. Probably because the giving of an engagement ring is his particular province, she very rarely gives him a ring or, in fact, any present at all.
The engagement ring is worn for the first time "in public" on the day of the announcement.
Usually a few days before the formal announcement--and still earlier for letters written abroad or to distant States--both young people write to their aunts, uncles, and cousins, and to their most intimate friends, of their engagement, asking them not to tell anyone until the determined date.
As soon as they receive the news, all the relatives of the groom-elect must call on the bride. She is not "welcomed by the family" until their cards, left upon her in person, assure her so. She must, of course, return all of these visits, and as soon as possible.
If his people are in the habit of entertaining, they should very soon ask her with her fiancé to lunch or to dinner, or after the engagement is publicly announced, give a dinner or tea or dance in her honor. If, on the other hand, they are very quiet people, their calling upon her is sufficient in itself to show their welcome.
In case of a recent death in either immediate family, the engagement cannot be publicly announced until the first period of mourning is past. (It is entirely dignified for a private wedding to take place at the bedside of a very ill parent, or soon after a deep bereavement. In that case there is, of course, no celebration, and the service is read in the presence of the immediate families only.)
The announcement is invariably made by the parents of the bride-elect. It is a breach of etiquette for a member of the young man's family to tell of the engagement until the formal announcement has been arranged for.