This is, of course, a matter of personal opinion. My own view is that the term “Gilded Age” is a fair description of this time period. The Gilded Age is generally said to have occurred between about 1870 and 1900. Twain gave the time period this name (he did so in 1873) because he felt that the society of the time looked good on the outside but was actually corrupt beneath. I would say that this time was certainly sparkly on the outside, at least for many people, and it was definitely much less glittery underneath.
It is hard to argue that the Gilded Age did not look good on the outside. This was a time when men like John D. Rockefeller and Andrew Carnegie were becoming extremely wealthy. They were able to live lives of conspicuous consumption. This was also a time when the Boston Symphony (1881) and the New York Metropolitan Opera (1883) were founded. The Brooklyn Bridge opened in 1883 as well, and the Columbian Exhibition in Chicago went on in 1893, showing that progress was happening on many fronts. In all of these ways and more, American society seemed to be glittering on the outside.
But all was not well beneath the surface. The great wealth of the “robber barons” was built on the labor of huge numbers of poor people. It was in 1890 that Jacob Riis published his book How the Other Half Lives, in which he looked at the terrible living conditions in the urban tenements of the time. It was a time when the masses of immigrants in cities were being organized into support for corrupt urban political machines. It was a time when business leaders like Carnegie used violence to put down strikes. All of these things show that things beneath the surface of Gilded Age society were often ugly and corrupt. For these reasons, I would tend to argue that it is fair to call this time a Gilded Age.