This paper discusses Stardog, an RDF database with strong support for SPARQL and OWL (it supports all of OWL 2) that can be extended to provide labelled property graph capabilities with support for Apache Tinkerpop and Gremlin. The Lucene search engine has been embedded into Stardog. The database is ACID compliant and supports immediate consistency. It is currently only available on-premises, but the company is working on a cloud-enabled version.
That said, the emphasis in Stardog is on building and supporting enterprise knowledge graphs, where you want to be able to view information and relationships – and explore these – across multiple, heterogeneous data sources.