There are currently 3 ways for certain eligible candidates to obtain Luxembourg Dual Citizenship.
The below gives a quick overview of eligibility:
Recover Luxembourg Citizenship
(Article 89 – Pre-Qualified Candidates Only)
–For Pre-Qualified candidates who submitted to Luxembourg an initial application letter by 12/31/2018. If you did not submit your initial application before the December 31, 2018 deadline, you are no longer eligible to apply.
-You received a Luxembourg Ancestor Certificate in the mail (see image)
-You are planning a trip to Luxembourg in 3-4 months and want help