# Which similar properties must objects have to sustain quantum entanglement?

Quantum entanglement occurs when particles such as photons, electrons, molecules as large as buckyballs, and even small diamonds interact physically and then become separated; the type of interaction is such that each resulting member of a pair is properly described by the same quantum mechanical description (state), which is indefinite in terms of important factors such as position,momentum, spin, polarization, etc. Source: Wikipedia

All objects can get quantumly entangled, but to get a more sustained quantum entanglement with a long dechoherence time, the objects has to have equal properties. Do all properties have to be equal or could some properties be different?

For instance: Form seem to be important for quantum entanglement, but is size important? Could a small diamond be quantum entangled with a larger diamond with the same shape?

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Question updated and clarified with information from John's answer. – Enos Oye Mar 6 '13 at 11:21

I can't get at the original paper describing the experiment because it's behind a paywall, but some Googling for related papers like this one suggests that the vibrational excitations in diamond are unusually resistant to decoherence for technical reasons that I must admit I didn't really grasp. The decoherence time is around 23$\mu$s, which is eternity as decoherence times for macroscopic objects go!