The Collaborative International Dictionary of English v.0.48:

Diversification \Di*ver`si*fi*ca"tion\, n. [See Diversify.]
   1. The act of making various, or of changing form or quality.
      --Boyle.
      [1913 Webster]

   2. State of diversity or variation; variegation;
      modification; change; alternation.
      [1913 Webster]

            Infinite diversifications of tints may be produced.
                                                  --Adventurer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

diversification
    n 1: the act of introducing variety (especially in investments
         or in the variety of goods and services offered); "my
         broker recommended a greater diversification of my
         investments"; "he limited his losses by diversification of
         his product line" [syn: diversification, variegation]
    2: the condition of being varied; "that restaurant's menu lacks
       diversification; every day it is the same"

Moby Thesaurus II by Grady Ward, 1.0:

127 Moby Thesaurus words for "diversification":
   Proteus, about-face, accommodation, adaptation, adjustment,
   allotropism, allotropy, alteration, amelioration, analysis,
   anatomization, apostasy, atomization, betterment, break,
   capriciousness, change, change of heart, changeability,
   changeableness, choppiness, constructive change, continuity,
   conversion, dappleness, defection, degeneration,
   degenerative change, demarcation, desynonymization, deterioration,
   deviation, difference, differencing, differentiation,
   discontinuity, discrimination, disequalization, disjunction,
   disorder, distinction, distinguishment, divarication, divergence,
   diversion, diversity, division, fitting, flip-flop, gradual change,
   her infinite variety, heterogeneity, heteromorphism, improvement,
   inconsistency, inconstancy, individualization, individuation,
   inequality, instability, irregularity, jerkiness, manifoldness,
   melioration, mercuriality, mitigation, modification, modulation,
   motleyness, multifariousness, multiplicity, mutability,
   nonconformism, nonconformity, nonstandardization, nonuniformity,
   omnifariousness, omniformity, overthrow, particularization,
   personalization, pluralism, polymorphism, qualification,
   radical change, raggedness, re-creation, realignment, redesign,
   reform, reformation, remaking, renewal, reshaping, restructuring,
   reversal, revival, revivification, revolution, segregation,
   separation, severalization, severance, shapeshifter, shift,
   specialization, sudden change, switch, total change, transition,
   turn, turnabout, unconformism, unconformity, unevenness,
   unorthodoxy, unsteadiness, upheaval, variability, variation,
   variegation, variety, variousness, versatility, violent change,
   wavering, worsening