Glass and method for manufacturing the same

A glass, comprising:

• a first glass portion;
• and
• a second glass portion,
• wherein
• the first glass portion has a composition that forms a glass having a property that, out of plastic deformation characteristics, plastic flow is more dominant than in the second glass portion,
• the second glass portion has a composition that forms a glass having a property that, out of the plastic deformation characteristics, densification is more dominant than in the first glass portion,
• in indentation depth measurement using indentation with a Vickers indenter, recovery of indentation depth of the glass having the composition that forms the first glass portion is lower than recovery of indentation depth of the glass having the composition that forms the second glass portion, the recovery of indentation depth RID being given by (Db−Da)/Db, where Db represents an indentation depth before heat treatment at a glass transition temperature, and Da represents an indentation depth after the heat treatment at the glass transition temperature,
• the first glass portion includes a first glass region having a first glass composition with the recovery of indentation depth of less than 0.35, and
• the second glass portion includes a second glass region having a second glass composition with the recovery of indentation depth of 0.35 or more.