For Cold War Diplomacy that provides an overview and some historiography, see:

1. Melvyn P. Leffler, For the Soul of Mankind: The United States, the Soviet Union, and the Cold War (2008)
2. Frank Costigliola and Michael J. Hogan (eds.) America in the World: The Historiography of American Foreign Relations since 1941 (2013)
3. Robert McMahon (ed.) The Cold War in the Third World (Oxford, 2013)
4. Melvyn P. Leffler and Odd Arne Westad (eds.), The Cambridge History of the Cold War

Henry Kissinger's, Diplomacy, provides a good background on the evolution of European diplomacy.

Howard Jones, Crucible of Power: A History of US Foreign Relations since 1897 is a good choice for recent American diplomacy.

For US Chinese relations, see: Michael H. Hunt, The Making of a Special Relationship, The United States and China to 1914.

Anything by John Gaddis is worth reading, though that is going to be a very pro-American National Security school interpretation. That should start you off.

I have tons of additional citations for Cold War Diplomacy, less so on periods preceding it. So if you want more let me know.

Hope it helps.

Do you want books that give a general overview of diplomacy, a more detailed blow-by-blow of diplomatic efforts in a specific case, or something more in between? I have a few of the latter two books I could recommend.

In the specifics category, The Diplomacy of the French-Sino War (1883-1885) is exactly what it says on the tin, and should be quite reasonable affordable. Skewing more general, Great Power Diplomacy, 1814-1914 by Norman Rich is a handy textbook, and Ottoman Seapower and Levantine Diplomacy in the Age of Discovery is a good read that talks about the strategic considerations and diplomatic and military efforts to address them.