It could be a city or town crest rather than a family one.
Many cities have a "castle triple turreted" as their crest. Some on rocks, some with water underneath, some with walls, some with birds etc. This one has "laurel leaves" either "erect" or "proper" over the castle
I can't see a city or town that has the castle and the laurel leaves -although there may be one.
Regarding the Gibralta question - that line of stone underneath the castle could perhaps be the artist's representation of the rock.
Thinking about a family crest - I did come across this chap - who has a crest which fits the description. unfortunately, if your friends just bought the items I suppose it unlikely that these names would help.
Sir CLEMENT LLOYD HILL, Knight Commander of
the Most Distinguished Order of Saint Michael and Saint
George. Born May 5, 1845, being the third son of the Rev.
John Hill (second brother of the Rt. Hon. the second Vis-
count Hill), by his wife Charlotte, daughter of Iliomas
Kenyon, Esquire, commonly known as the Honourable
Thomas Kenyon; created Knight Commander of the
Most Distinguished Order of Saint Michael and Saint
George, 1887.
.....
and for his Crest, upon a wreath of the colours, a castle triple-turreted,
surmounted with a garland of laurel proper ; with the Motto,'
" Avancez."
There is an example here..
http://www.rootschat.com/links/0aim/ It looks quite similar - although iI would have thought if it was this family it should have had the motto scroll underneath the castle.
Milly