Advent wreaths traditionally consist of a circle of evergreen branches with four candles, three purple and one pink or rose colored. The purple candles symbolize the prayer, penance and preparation that mark the Advent season. The rose-colored or pink candle coincides with the Third Sunday of Advent, Gaudete Sunday. The Third Sunday of Advent, on which the priest also wears pink or rose, is a time of celebration, noting that Advent is nearing completion and Christmas is near.
During Advent, candles are progressively lit week by week, beginning with a single purple candle. During the second week, two purple candles are lit, followed by two purple candles and the pink candle during the third week, and then all four candles.
The blessing of an Advent Wreath traditionally takes place on the First Sunday of Advent or on the evening before the First Sunday of Advent. When the blessing of the Advent Wreath is celebrated in the home, it is appropriate that it be blessed by a parent or another member of the family.
The blessing below is from "Catholic Household Blessings and Prayers," as used on the USCCB website.
The Blessing of an Advent Wreath
All make the sign of the cross as the leader says:
Our help is in the name of the Lord.
Response (R/.) Who made heaven and earth.
Reader: The Word of the Lord.
R/. Thanks be to God.
With hands joined, the leader says:
Lord our God,
we praise you for your Son, Jesus Christ:
he is Emmanuel, the hope of the peoples,
he is the wisdom that teaches and guides us,
he is the Savior of every nation.
let your blessing come upon us
as we light the candles of this wreath.
May the wreath and its light
be a sign of Christ’s promise to bring us salvation.
May he come quickly and not delay.
We ask this through Christ our Lord.
The blessing may conclude with a verse from
“O Come, O Come, Emmanuel”:
O come, desire of nations, bind
in one the hearts of humankind;
bid ev’ry sad division cease
and be thyself our Prince of peace.
Rejoice! Rejoice! Emmanuel
shall come to thee, O Israel.