It is possible to speed up creation/rebuild process of a large index using keywords PARALLEL, and NOLOGGING:

ALTER SESSION ENABLE PARALLEL DDL;

CREATE INDEX INDEX_OWNER.INDEX_NAME
ON TABLE_NAME ( col1 , col2, ..)
NOLOGGING PARALLEL
TABLESPACE TABLESPACE_NAME
/

-- or
ALTER INDEX INDEX_OWNER.INDEX_NAME
REBUILD NOLOGGING PARALLEL
/

Don’t forget to set back LOGGING and NOPARALLEL options, because create/rebuild will set these options.

ALTER INDEX INDEX_OWNER.INDEX_NAME LOGGING NOPARALLEL;

Estimate statistics:

BEGIN
DBMS_STATS.GATHER_INDEX_STATS(
OWNNAME => 'INDEX_OWNER'
,INDNAME => 'INDEX_NAME'
-- Based on index size, for large indexes as
-- as low as 3% or Oracle can decide using:
-- DBMS_STATS.AUTO_SAMPLE_SIZE
, ESTIMATE_PERCENT => 10
-- use PARALLELISM
, DEGREE => DBMS_STATS.DEFAULT_DEGREE
);
END;
/

Warning: By using PARALLEL keywords you can easily exhaust all the server resources, which could cause problems on a production system, use with caution and on your own risk.