It's hard to date this comprehensively as there's not a lot of detail visible, between the damage, the size of the portrait (upper chest and head only), and the dark coat and background.

The colored neck-cloth came into fashion in the late 1820s, and as it did the turned-up collar began to shrink and loosen - as far as that aspect of the portrait goes, this could range from ca. 1825 to ca. 1860, though by about 1850 the cloth would probably not be worn so high on the neck. Throughout that same period, it was also common for a man's waistcoat to show that much of his shirtfront.

In English and America portraiture of this period, it's extremely common for there to be some facial hair - if not a beard running under the chin or whiskers low on the jawline, then sideburns. I'm not sure if this sitter's lack of facial hair is reflective of a Spanish trend that might give additional dating information.

The shape of the coat collar/lapels sloping down from his neck indicates a date before 1850 or so. It's unfortunate that we can't see the tops of the coat sleeves, which would provide a bit more information as well.

I can't really speak to the jewelry, so the last clue we can examine is his smoking cap. Soft caps had been a part of men's informal dress since the days of wigs; in the early nineteenth century, it was fashionable to make them a bit more structured (with a round crown and the body sewn around it to form a toque), and often decorated with embroidery and a tassel for a Middle Eastern flair. These were worn from the late 1840s through the 1860s at least - it's hard to say exactly when they stopped being worn, as they were so informal that they were not typically shown in portraits and other types of artwork. Gentlemen who smoked at home during the mid-nineteenth century typically changed into the cap and a smoking jacket in order to keep the smell, considered ungenteel, contained to one room and one set of clothes; the cap would keep the smell of cigar or cigarette smoke from clinging to the hair.

So, all in all, I'd say that the late 1840s are the most likely period for this portrait. Hope this is helpful!